Connection pooler for replica (#1127)

* Enable connection pooler for replica
* Refactor code for connection pooler
  - Move all the relevant code to a separate file
  - Move all the related tests to a separate file
  - Avoid using cluster where not required
  - Simplify the logic in sync and other methods
  - Cleanup of duplicated or unused code
* Fix labels for the replica pods
* Update deleteConnectionPooler to include role
* Adding test cases and other changes
   - Fix unit test and delete secret when required only
   - Make sure we use empty fresh cluster for every test case.
* enhance e2e test
* Disable pooler in complete manifest as this is source for e2e too an creates unnecessary pooler setups.

Co-authored-by: Rafia Sabih <rafia.sabih@zalando.de>
Co-authored-by: Jan Mussler <janm81@gmail.com>

pkg/cluster/database.go

@@ -473,8 +473,8 @@ func (c *Cluster) execCreateOrAlterExtension(extName, schemaName, statement, doi
 }
 
 // Creates a connection pool credentials lookup function in every database to
-// perform remote authentification.
-func (c *Cluster) installLookupFunction(poolerSchema, poolerUser string) error {
+// perform remote authentication.
+func (c *Cluster) installLookupFunction(poolerSchema, poolerUser string, role PostgresRole) error {
 	var stmtBytes bytes.Buffer
 
 	c.logger.Info("Installing lookup function")
@@ -567,12 +567,11 @@ func (c *Cluster) installLookupFunction(poolerSchema, poolerUser string) error {
 			failedDatabases = append(failedDatabases, dbname)
 			continue
 		}
-
 		c.logger.Infof("pooler lookup function installed into %s", dbname)
 	}
 
 	if len(failedDatabases) == 0 {
-		c.ConnectionPooler.LookupFunction = true
+		c.ConnectionPooler[role].LookupFunction = true
 	}
 
 	return nil