Reduce Android minSdkVersion back to 23

[a-maurice]

Description

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

As part of the Android tools update, we had bumped the minSdkVersion to 24. This was to workaround a bug with dexing, but there are a couple other workarounds, including using proguard or specifying a different r8 version to use. So, this change reduces the version back to 23, and adds the r8 change to the integration tests.

For some more info, see googlesamples/unity-jar-resolver#703

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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.

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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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Notes

• Bug fixes and feature changes require an update to the Release Notes section of release_build_files/readme.md.
• Read the contribution guidelines CONTRIBUTING.md.
• Changes to the public API require an internal API review. If you'd like to help us make Firebase APIs better, please propose your change in a feature request so that we can discuss it together.

[github-actions]

Integration test with FLAKINESS (succeeded after retry)

Requested by @a-maurice on commit 2437818
Last updated: Thu Oct 10 13:40 PDT 2024
View integration test log & download artifacts

Failures	Configs
gma	[TEST] [FLAKINESS] [Android] [1/3 os: windows] [1/2 android_device: android_target] (1 failed tests)   FirebaseGmaTest.TestAdViewLoadAdGetInlineAdaptiveBannerMaxHeight

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