RUM-2451: Run functional tests against different AGP versions

[0xnm]

What does this PR do?

Because of the way GradleRunner#withPluginClasspath works we were actually running E2E tests always with the AGP version plugin was compiled against.

This PR fixes it, now we will run tests for AGP 7.0.4 and AGP 8.2.0.

Also few issues were discovered thanks to the proper test runs, and they are fixed with this PR as well.

Review checklist (to be filled by reviewers)

• [ ] Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• [ ] Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• [ ] Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

[codecov-commenter]

Codecov Report

Merging #214 (4004475) into develop (ee172eb) will increase coverage by 0.27%. The diff coverage is 0.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #214 +/- ## ============================================= + Coverage 77.93% 78.20% +0.27% - Complexity 186 187 +1 ============================================= Files 22 22 Lines 666 665 -1 Branches 85 85 ============================================= + Hits 519 520 +1 + Misses 117 116 -1 + Partials 30 29 -1 ``` | [Files](https://app.codecov.io/gh/DataDog/dd-sdk-android-gradle-plugin/pull/214?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DataDog) | Coverage Δ | | |---|---|---| | [...com/datadog/gradle/plugin/DdAndroidGradlePlugin.kt](https://app.codecov.io/gh/DataDog/dd-sdk-android-gradle-plugin/pull/214?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DataDog#diff-ZGQtc2RrLWFuZHJvaWQtZ3JhZGxlLXBsdWdpbi9zcmMvbWFpbi9rb3RsaW4vY29tL2RhdGFkb2cvZ3JhZGxlL3BsdWdpbi9EZEFuZHJvaWRHcmFkbGVQbHVnaW4ua3Q=) | `54.97% <0.00%> (+0.90%)` | :arrow_up: |