Require manual Android Play version codes and draft closed testing uploads

[jjoonleo]

Summary

• Remove the automatic push trigger from the Android internal Play workflow so internal uploads are manual-only.
• Require android_version_code for both internal and closed testing uploads and use it as the Android versionCode.
• Keep both Play workflows on draft releases and explicitly set changesNotSentForReview: true.
• Update release docs to reflect the manual version-code workflow.

Testing

• YAML syntax for both Play workflows parsed successfully.
• Checked the workflow diff for formatting and consistency.
• Verified the release docs no longer refer to github.run_number for Play uploads.