normalize Spanner CDC

[aIbrahiim]

Please add a meaningful description for your change here

---

Thank you for your contribution! Follow this checklist to help us incorporate your contribution quickly and easily:

• Mention the appropriate issue in your description (for example: addresses #123), if applicable. This will automatically add a link to the pull request in the issue. If you would like the issue to automatically close on merging the pull request, comment fixes #<ISSUE NUMBER> instead.
• Update CHANGES.md with noteworthy changes.
• If this contribution is large, please file an Apache Individual Contributor License Agreement.

See the Contributor Guide for more tips on how to make review process smoother.

To check the build health, please visit https://github.com/apache/beam/blob/master/.test-infra/BUILD_STATUS.md

GitHub Actions Tests Status (on master branch)

See CI.md for more information about GitHub Actions CI or the workflows README to see a list of phrases to trigger workflows.

[github-actions]

Checks are failing. Will not request review until checks are succeeding. If you'd like to override that behavior, comment assign set of reviewers

[github-actions]

Assigning reviewers:

R: @shunping for label python.

Note: If you would like to opt out of this review, comment assign to next reviewer.

Available commands:

• stop reviewer notifications - opt out of the automated review tooling
• remind me after tests pass - tag the comment author after tests pass
• waiting on author - shift the attention set back to the author (any comment or push by the author will return the attention set to the reviewers)

The PR bot will only process comments in the main thread (not review comments).

[Abacn]

Either way, this requires pipeline submission time access to the Spanner instance. As a follow up, to allow pass a schema so that it won't need IO resource access at pipeline submission time, or create a Issue to track

[aIbrahiim]

ok and yes both still need Spanner access at expansion and submission time

I'll create a follow up issue to allow an optional schema config on the Spanner CDC SchemaTransform so expansion can skip live information_schema access when the schema is provided

[Abacn]

Two things unusual

• allowedTableNames is a Set and we're doing a linear search
• equalsIgnoreCase. Is table name supposed to be case inSensitive?