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>

charts/postgres-operator/crds/postgresqls.yaml

@@ -190,6 +190,8 @@ spec:
                 type: string
               enableConnectionPooler:
                 type: boolean
+              enableReplicaConnectionPooler:
+                type: boolean
               enableLogicalBackup:
                 type: boolean
               enableMasterLoadBalancer:
@@ -603,4 +605,4 @@ spec:
           status:
             type: object
             additionalProperties:
-              type: string
+              type: string