Description

This PR tries to solve a memory leak in Google maps where the number of ActivityLifecycleCallbacks would increase every time the FlutterActivity is created, as the previous reference was not removed.

Related Issues

flutter/flutter#36520

Checklist

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• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• My PR includes unit or integration tests for all changed/updated/fixed behaviors (See [Contributor Guide]).
• All existing and new tests are passing.
• I updated/added relevant documentation (doc comments with ///).
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Breaking Change

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• Yes, this is a breaking change (please indicate a breaking change in CHANGELOG.md and increment major revision).
• No, this is not a breaking change.