chore: do not use pg_settings due to a bug in the emulator

The emulator crashes when executing a query on pg_catalog.pg_settings.
Remove the references to pg_catalog.pg_settings for now, as all the
data comes from the in-memory CTE anyways.

src/main/java/com/google/cloud/spanner/pgadapter/ConnectionHandler.java

@@ -276,6 +276,7 @@ public void connectToSpanner(String database, @Nullable Credentials credentials)
   @VisibleForTesting
   static String buildConnectionURL(
       String database, OptionsMetadata options, Properties properties) {
+    boolean checkForCredentials = true;
     String uri =
         options.hasDefaultConnectionUrl()
             ? options.getDefaultConnectionUrl()

src/main/java/com/google/cloud/spanner/pgadapter/metadata/OptionsMetadata.java

@@ -1024,6 +1024,14 @@ public String buildConnectionURL(String database) {
       host = environment.get(SPANNER_EMULATOR_HOST_ENV_VAR);
       usePlainText = true;
     }
+    if (propertyMap != null
+        && Boolean.parseBoolean(propertyMap.getOrDefault("autoConfigEmulator", "false"))) {
+      usePlainText = true;
+    }
+    if (propertyMap != null
+        && Boolean.parseBoolean(propertyMap.getOrDefault("usePlainText", "false"))) {
+      usePlainText = true;
+    }
     String endpoint;
     if (host.isEmpty()) {
       endpoint = "cloudspanner:/";
@@ -1041,8 +1049,7 @@ public String buildConnectionURL(String database) {
     // Note that Credentials here is the credentials file, not the actual credentials
     String url = String.format("%s%s;userAgent=%s", endpoint, databaseName, DEFAULT_USER_AGENT);
 
-    if (!shouldAuthenticate()
-        && Strings.isNullOrEmpty(environment.get(SPANNER_EMULATOR_HOST_ENV_VAR))) {
+    if (!shouldAuthenticate() && !usePlainText) {
       String credentials = buildCredentialsFile();
       if (!Strings.isNullOrEmpty(credentials)) {
         url = String.format("%s;credentials=%s", url, credentials);

src/main/java/com/google/cloud/spanner/pgadapter/session/SessionState.java

@@ -145,16 +145,19 @@ public String generatePGSettingsCte() {
         + "\n),\n"
         + "pg_settings_names_ as (\n"
         + "select name from pg_settings_inmem_\n"
-        + "union\n"
-        + "select name from pg_catalog.pg_settings\n"
+        // TODO: Re-enable when the pg_settings table in the emulator has been fixed.
+        // + "union\n"
+        // + "select name from pg_catalog.pg_settings\n"
         + "),\n"
         + "pg_settings as (\n"
         + "select n.name, "
         + generatePgSettingsColumnExpressions()
         + "\n"
         + "from pg_settings_names_ n\n"
         + "left join pg_settings_inmem_ s1 using (name)\n"
-        + "left join pg_catalog.pg_settings s2 using (name)\n"
+        // TODO: Re-enable when the pg_settings table in the emulator has been fixed.
+        // + "left join pg_catalog.pg_settings s2 using (name)\n"
+        + "left join pg_settings_inmem_ s2 using (name)\n"
         + "order by name\n"
         + ")\n";
   }

src/test/java/com/google/cloud/spanner/pgadapter/ConnectionHandlerTest.java

@@ -689,7 +689,7 @@ public void testBuildConnectionUrl() {
     // Enable the autoConfigEmulator flag through the options builder.
     OptionsMetadata emulatorOptions = OptionsMetadata.newBuilder().autoConfigureEmulator().build();
     assertEquals(
-        "cloudspanner:/projects/my-project/instances/my-instance/databases/my-database;userAgent=pg-adapter;autoConfigEmulator=true;dialect=postgresql",
+        "cloudspanner:/projects/my-project/instances/my-instance/databases/my-database;userAgent=pg-adapter;usePlainText=true;autoConfigEmulator=true;dialect=postgresql",
         buildConnectionURL(
             "projects/my-project/instances/my-instance/databases/my-database",
             emulatorOptions,

src/test/java/com/google/cloud/spanner/pgadapter/session/SessionStateTest.java

@@ -441,14 +441,17 @@ static String getDefaultSessionStateExpression() {
         + "),\n"
         + "pg_settings_names_ as (\n"
         + "select name from pg_settings_inmem_\n"
-        + "union\n"
-        + "select name from pg_catalog.pg_settings\n"
+        // TODO: Re-enable when the pg_settings table in the emulator has been fixed.
+        // + "union\n"
+        // + "select name from pg_catalog.pg_settings\n"
         + "),\n"
         + "pg_settings as (\n"
         + "select n.name, coalesce(s1.setting, s2.setting) as setting,coalesce(s1.unit, s2.unit) as unit,coalesce(s1.category, s2.category) as category,coalesce(s1.short_desc, s2.short_desc) as short_desc,coalesce(s1.extra_desc, s2.extra_desc) as extra_desc,coalesce(s1.context, s2.context) as context,coalesce(s1.vartype, s2.vartype) as vartype,coalesce(s1.source, s2.source) as source,coalesce(s1.min_val, s2.min_val) as min_val,coalesce(s1.max_val, s2.max_val) as max_val,coalesce(s1.enumvals, s2.enumvals) as enumvals,coalesce(s1.boot_val, s2.boot_val) as boot_val,coalesce(s1.reset_val, s2.reset_val) as reset_val,coalesce(s1.sourcefile, s2.sourcefile) as sourcefile,coalesce(s1.sourceline, s2.sourceline) as sourceline,coalesce(s1.pending_restart, s2.pending_restart) as pending_restart\n"
         + "from pg_settings_names_ n\n"
         + "left join pg_settings_inmem_ s1 using (name)\n"
-        + "left join pg_catalog.pg_settings s2 using (name)\n"
+        // TODO: Re-enable when the pg_settings table in the emulator has been fixed.
+        // + "left join pg_catalog.pg_settings s2 using (name)\n"
+        + "left join pg_settings_inmem_ s2 using (name)\n"
         + "order by name\n"
         + ")\n";
   }