chore: remove owlbot

[JoeWang1127]

In this PR:

• Disable Owlbot and remove related files, please see go/disable-owlbot-java for more info.

[generated-files-bot]

Warning: This pull request is touching the following templated files:

• .github/generated-files-bot.yml
• codecov.yaml

[JoeWang1127]

CodeQL / Analyze (python) failed due to deletion of owlbot.py.

 /opt/hostedtoolcache/CodeQL/2.18.2/x64/codeql/codeql database finalize --finalize-dataset --threads=4 --ram=14567 /home/runner/work/_temp/codeql_databases/python
  CodeQL detected code written in Java/Kotlin, but not any written in Python. Confirm that there is some source code for Python in the project. For more information, review our troubleshooting guide at https://gh.io/troubleshooting-code-scanning/no-source-code-seen-during-build .
  Error: Encountered a fatal error while running "/opt/hostedtoolcache/CodeQL/2.18.2/x64/codeql/codeql database finalize --finalize-dataset --threads=4 --ram=14567 /home/runner/work/_temp/codeql_databases/python". Exit code was 32 and last log line was: CodeQL detected code written in Java/Kotlin, but not any written in Python. Confirm that there is some source code for Python in the project. For more information, review our troubleshooting guide at https://gh.io/troubleshooting-code-scanning/no-source-code-seen-during-build . See the logs for more details.

[diegomarquezp]

CodeQL / Analyze (python) failed due to deletion of owlbot.py.

 /opt/hostedtoolcache/CodeQL/2.18.2/x64/codeql/codeql database finalize --finalize-dataset --threads=4 --ram=14567 /home/runner/work/_temp/codeql_databases/python
  CodeQL detected code written in Java/Kotlin, but not any written in Python. Confirm that there is some source code for Python in the project. For more information, review our troubleshooting guide at https://gh.io/troubleshooting-code-scanning/no-source-code-seen-during-build .
  Error: Encountered a fatal error while running "/opt/hostedtoolcache/CodeQL/2.18.2/x64/codeql/codeql database finalize --finalize-dataset --threads=4 --ram=14567 /home/runner/work/_temp/codeql_databases/python". Exit code was 32 and last log line was: CodeQL detected code written in Java/Kotlin, but not any written in Python. Confirm that there is some source code for Python in the project. For more information, review our troubleshooting guide at https://gh.io/troubleshooting-code-scanning/no-source-code-seen-during-build . See the logs for more details.

googleapis/google-api-java-client#2508 (comment)