Enforce and validate just the dest dir on merge

This commit changes the `merge_catalog_dirs` to call the
`enforce_json_config_dir` and `opm_validate` only once after merging all
files into the destination dir.

Refers to CLOUDDST-21432

iib/workers/tasks/fbc_utils.py

@@ -93,11 +93,11 @@ def merge_catalogs_dirs(src_config: str, dest_config: str):
             msg = f"config directory does not exist: {conf_dir}"
             log.error(msg)
             raise IIBError(msg)
-        enforce_json_config_dir(conf_dir)
-        opm_validate(conf_dir)
 
     log.info("Merging config folders: %s to %s", src_config, dest_config)
     shutil.copytree(src_config, dest_config, dirs_exist_ok=True)
+    enforce_json_config_dir(conf_dir)
+    opm_validate(conf_dir)
 
 
 def extract_fbc_fragment(temp_dir: str, fbc_fragment: str) -> Tuple[str, str]:

tests/test_workers/test_tasks/test_fbc_utils.py

@@ -117,23 +117,10 @@ def test_merge_catalogs_dirs(mock_enforce_json, mock_rc, mock_opm, tmpdir):
         tempfile.NamedTemporaryFile(dir=operator_dir, delete=False)
 
     merge_catalogs_dirs(src_config=source_dir, dest_config=destination_dir)
-    mock_enforce_json.assert_has_calls(
-        [
-            mock.call(source_dir),
-            mock.call(destination_dir),
-        ]
-    )
-    mock_rc.assert_has_calls(
-        [
-            mock.call(
-                [mock_opm.opm_version, 'validate', source_dir],
-                exc_msg=f'Failed to validate the content from config_dir {source_dir}',
-            ),
-            mock.call(
-                [mock_opm.opm_version, 'validate', destination_dir],
-                exc_msg=f'Failed to validate the content from config_dir {destination_dir}',
-            ),
-        ]
+    mock_enforce_json.assert_called_once_with(destination_dir)
+    mock_rc.called_once_with(
+        [mock_opm.opm_version, 'validate', destination_dir],
+        exc_msg=f'Failed to validate the content from config_dir {destination_dir}',
     )
 
     for r, d, f in os.walk(source_dir):