Upgrade GCJ to make Trace with Logging work (#1446)

Tested that upgrading to latest Google Cloud Java version
resolves #1118. Issue #780 also seems to have gone away.

Fixes #780.
Fixes #1118.

spring-cloud-gcp-dependencies/pom.xml

@@ -16,7 +16,7 @@
 	<packaging>pom</packaging>
 
 	<properties>
-		<google-cloud-bom.version>0.78.0-alpha</google-cloud-bom.version>
+		<google-cloud-bom.version>0.79.0-alpha</google-cloud-bom.version>
 		<google-auth-library-oauth2-http.version>0.13.0</google-auth-library-oauth2-http.version>
 		<cloud-sql-socket-factory.version>1.0.12</cloud-sql-socket-factory.version>
 	</properties>

spring-cloud-gcp-samples/spring-cloud-gcp-trace-sample/src/main/appengine/app.yaml

@@ -10,8 +10,7 @@ manual_scaling:
 
 resources:
   memory_gb: 4
-
-env_variables:
-  # on App Engine flexible environment, logging flush level must be the same as the log level
-  # see: https://github.com/spring-cloud/spring-cloud-gcp/issues/1096
-  STACKDRIVER_LOG_FLUSH_LEVEL: 'INFO'
+#env_variables:
+#  # on App Engine flexible environment, logging flush level must be the same as the log level
+#  # see: https://github.com/spring-cloud/spring-cloud-gcp/issues/1096
+#  STACKDRIVER_LOG_FLUSH_LEVEL: 'INFO'