chore: set Java generator releaseVersion to 2.9.2 (#33407)

Client versions are {apiVersion}-rev{revision}-{releaseVersion}, and only
versions not yet on Maven Central are released. Bumping releaseVersion gives
every client a new version so all clients are re-released with
google-api-client 2.9.2.

Author: blakeli0

generator/src/googleapis/codegen/languages/java/2.0.0/features.json

@@ -2,7 +2,7 @@
   "language": "java",
   "description": "Java libraries for Google APIs.",
   "generator": "java1_15",
-  "releaseVersion": "2.0.0",
+  "releaseVersion": "2.9.2",
   "baseClientLibrary": "2.9.2",
   "descriptor_additions": {
     "proguard-config": "proguard-google-api-client.txt",