Bumping CI to Test Against JDK 21. This is part of the setup to use a robolectric version that supports SDK 36. This new robolectric version requires JDK 21 at minimum.

Edit: On JDK 21+ an error is thrown for this-escape warning due to: https://bugs.openjdk.org/browse/JDK-8015831. Addressing the warning requires removing the abstract funciton `createExoPlayerEventListener` in base class `VideoPlayer.java`, which could cause unknown regressions. Keeping the behavior as-is since the plugin works as expected. 

Addresses flutter/flutter#163071
Addresses flutter/flutter#177674

## Pre-Review Checklist

**Note**: The Flutter team is currently trialing the use of [Gemini Code Assist for GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code). Comments from the `gemini-code-assist` bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed.

[^1]: Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling.

Deprecates `dartHostTestHandler`, in preparation for removing sometime in 2026 if no significant new information comes to light.

Part of flutter/flutter#178322

## Pre-Review Checklist

[^1]: Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling.

…y Android and iOS is supported. (#10385)

## Pre-Review Checklist

**Note**: The Flutter team is currently trialing the use of [Gemini Code Assist for GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code). Comments from the `gemini-code-assist` bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed.

[^1]: Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling.

typo: from "recieve" to "receive"; from "use" to "using"
updated changelog to 7.2.4
discovered while investigating how to use google_sign_in auth for android and found: #10246

## Pre-Review Checklist

**Note**: The Flutter team is currently trialing the use of [Gemini Code Assist for GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code). Comments from the `gemini-code-assist` bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed.

[^1]: Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling.