Revert super_read_only config file changes (#10366)

* Revert super_read_only config file changes

This ended up causing various failures when that change was applied
in mysqlctl by updating its rice box (make embed_config). You can see
this in: #10094

We're instead going to schedule work to add full super_read_only
support to Vitess in: #10363

* Remove MySQL 5.6 config

This is a follow-up to #10295

Makefile

@@ -49,8 +49,7 @@ export CGO_CFLAGS := -O1
 
 # regenerate rice-box.go when any of the .cnf files change
 embed_config:
-	cd go/vt/mysqlctl && go run github.com/GeertJohan/go.rice/rice embed-go
-	cd go/vt/mysqlctl && go build .
+	cd go/vt/mysqlctl && go run github.com/GeertJohan/go.rice/rice embed-go && go build .
 
 # build the vitess binaries with dynamic dependency on libc
 build-dyn:

config/mycnf/mysql57.cnf

@@ -12,9 +12,6 @@ relay_log_info_repository = TABLE
 relay_log_purge = 1
 relay_log_recovery = 1
 
-# we should never need super privileges
-super-read-only
-
 # In MySQL 5.7 the default charset is latin1
 
 character_set_server = utf8

config/mycnf/mysql80.cnf

@@ -11,9 +11,6 @@ binlog_expire_logs_seconds = 259200
 # disable mysqlx
 mysqlx = 0
 
-# we should never need super privileges
-super-read-only
-
 # 8.0 changes the default auth-plugin to caching_sha2_password
 default_authentication_plugin = mysql_native_password