chore: cleanup release-please config (#2461)

* chore: add release-please config for protobuf-4.x

* feat: configure rc releases to be on prerelease mode

* fix: next release candidate

* chore: cleanup release-please config

- Remove redundant options already declared at the top level.\n- Remove bumpMinorPreMajor for repositories after the first major release.

* refactor: move common release-please options to top level

* revert: revert changes to release-please-config.json

Author: diegomarquezp

.github/release-please.yml

@@ -1,29 +1,11 @@
 handleGHRelease: true
 manifest: true
+bumpMinorPreMajor: true
+packageName: gcp-lts-bom
 branches:
-  - bumpMinorPreMajor: true
-    handleGHRelease: true
-    packageName: gcp-lts-bom
-    manifest: true
-    branch: 9.0.x-lts
-  - bumpMinorPreMajor: true
-    handleGHRelease: true
-    packageName: gcp-lts-bom
-    manifest: true
-    branch: 8.0.x-lts
-  - bumpMinorPreMajor: true
-    handleGHRelease: true
-    packageName: gcp-lts-bom
-    manifest: true
-    branch: 7.0.x-lts
-  - bumpMinorPreMajor: true
-    handleGHRelease: true
-    packageName: gcp-lts-bom
-    manifest: true
-    branch: 6.0.x-lts
-  - bumpMinorPreMajor: true
-    handleGHRelease: true
-    packageName: gcp-lts-bom
-    manifest: true
-    branch: protobuf-4.x-rc
-    releaseType: java-yoshi
+    - branch: 9.0.x-lts
+    - branch: 8.0.x-lts
+    - branch: 7.0.x-lts
+    - branch: 6.0.x-lts
+    - branch: protobuf-4.x-rc
+      releaseType: java-yoshi