[issue-1788] added firedbase tests

[irudykss]

Description

Fixes #1788

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Checklist

• I have followed Sample Guidelines from AUTHORING_GUIDE.MD
• README is updated to include all relevant information
• Tests pass: nox -s py-3.9 (see Test Environment Setup)
• Lint pass: nox -s lint (see Test Environment Setup)
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• Please merge this PR for me once it is approved

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[m-strzelczyk]

I need to find someone with access to the python-docs-samples-firestore project. To get this sorted I guess.

[m-strzelczyk]

I think I fixed whatever problems we had with the python-docs-samples-firestore, but now the tests seem to take forever. I guess we will soon just get a timeout error. Can you investigate?

[m-strzelczyk]

In the test project, I see that we did hit quota.

I guess there's some problem with the tests if we use up all 50k operations.

[BigBlackWolf]

Seems db contained a lot of records, because I tried to ran the tests in my environment and there was only ~700 read/write operations. After cleaning up project DB (#11863) the CI passed.