Add an API flag to restore_secrets script

[DellaBitta]

Description

Provide details of the change, and generalize the change in the PR title above.

Whenever I do local development I run restore_secrets, which updates all of the Google Services data for all of the products. This pollutes my local branch since normally I'm only working on one product.

This change adds an optional api flag so that you can checkout the secrets for only one product at a time.

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Testing

Describe how you've tested these changes. Link any manually triggered Integration tests or CPP binary SDK Packaging Github Action workflows, if applicable.

• Local testing.
• Integration Test CI

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Type of Change

Place an x the applicable box:

• Bug fix. Add the issue # below if applicable.
• New feature. A non-breaking change which adds functionality.
• Other, such as a build process or documentation change.

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[github-actions]

Integration test with FLAKINESS (succeeded after retry)

Requested by @DellaBitta on commit 5c3d695
Last updated: Fri Jun 17 13:14 PDT 2022
View integration test log & download artifacts

Failures	Configs
firestore	[TEST] [FLAKINESS] [Android] [1/3 os: ubuntu] [1/2 android_device: android_target] (1 failed tests)   CRASH/TIMEOUT [TEST] [FLAKINESS] [Android] [1/3 os: windows] [1/2 android_device: android_target] (1 failed tests)   TransactionTest.TestGetNonexistentDocumentThenCreate

Add flaky tests to go/fpl-cpp-flake-tracker

[sunmou99]

Good idea. And what about make it a list of api?
flags.DEFINE_list("apis", None, "Retrieve secret for the particular SDKs only.")

[DellaBitta]

Is there a usecase for this? Generally we're only working on one API/SDK at a time, or all at the same time in the case of CI.

[sunmou99]

e.g. When someone tries to build only the failed testapps locally.

[DellaBitta]

Done! PTAL!