add local component-cli to path

`cli.py pipeline component_descriptor` command was originally used for
migration from (deprecated) "component-cli" (golang binary) to
drop-in-replacement in this repository (bin/component-cli). Back then,
it made sense for the command to not implicitly add aforementioned
replacement to PATH.

With migration being done over a year ago, it appears adequate to make
the command more convenient, and let it add component-cli to PATH. Add
it to end of path to still allow callers to use local component-cli.

cli/gardener_ci/pipeline.py

@@ -18,6 +18,7 @@
 logger = logging.getLogger('pipeline-cli')
 
 own_dir = os.path.abspath(os.path.dirname(__file__))
+cc_utils_root = os.path.join(own_dir, '../..')
 
 
 def _branch_cfg(
@@ -438,6 +439,13 @@ def component_descriptor(
         'ADD_DEPENDENCIES_CMD': dependencies_cmd,
     }
 
+    component_cli_path = os.path.join(
+        cc_utils_root,
+        'bin',
+    )
+    path = f'{os.environ.get('PATH', '')}:{component_cli_path}'
+    env['PATH'] = path
+
     subprocess.run(
         (component_descriptor_script,),
         env=env,