chore: use prerelease mode only

Removed prerelease settings and adjusted branch for release.

Author: diegomarquezp

.github/release-please.yml

@@ -9,11 +9,5 @@ branches:
 - bumpMinorPreMajor: true
   handleGHRelease: true
   releaseType: java-yoshi
-  prereleaseType: rc
   prerelease: true
-  branch: test-protobuf-4.x-prerelease
-- bumpMinorPreMajor: true
-  handleGHRelease: true
-  releaseType: java-yoshi
-  releaseAs: 2.0.0-rc1
   branch: test-protobuf-4.x-rc