chore(librarian): onboard to librarian (#2233)

Towards googleapis/librarian#2456 Files removed which are no longer used - Owlbot config files, including owlbot.py - Sync repo settings config file - Release please config files --------- Co-authored-by: ohmayr <omairn@google.com>

Author: parthea

.github/.OwlBot.lock.yaml

@@ -0,0 +1,10 @@
+image: us-central1-docker.pkg.dev/cloud-sdk-librarian-prod/images-prod/python-librarian-generator@sha256:c8612d3fffb3f6a32353b2d1abd16b61e87811866f7ec9d65b59b02eb452a620
+libraries:
+ - id: bigframes
+ version: 2.28.0
+ apis: []
+ source_roots:
+ - .
+ preserve_regex: []
+ remove_regex: []
+ tag_format: v{version}