Remove Bintray-sunset hacks

[d4vidi]

Description

During work on omitting Bintray (jfrog) from the repos list (#2734), some hacks were introduced in order to cope with the fact that not all artifacts are available on maven-central (in all versions). This is a follow-up on that. In particular, 2 main things to reiterate:

1. Revisit the need for the now-proprietarily stored (on Github) proguard-annotations.jar artifact (which is needed indirectly by RN itself).
2. Revisit all BINTRAY_SUNSET_HACK notations in the Gradle scripts, and see whether these hacks can be removed. Some are related to point 1.

Associated discussions:

• Please publish yoga-layout on Maven Central facebook/yoga#1065 (comment)
• [Deadline: Feb 1st, 2022] JCenter is being sunset -- What's the plan for react-native? react-native-community/discussions-and-proposals#331

[d4vidi]

Well looks like we could soon remove hacks much easier than we thought:

UPDATE 4/27/2021: We listened to the community and will keep JCenter as a read-only repository indefinitely. Our customers and the community can continue to rely on JCenter as a reliable mirror for Java packages.

https://jfrog.com/blog/into-the-sunset-bintray-jcenter-gocenter-and-chartcenter/