fix: manage graalvm image versions via Hermetic Build templates _only_ (#3800)

So far these versions are managed both by renovate-bot and Hermetic
Build. Since each release of Hermetic Build keeps these template
versions up to date, it's better suited to manage these versions via
Hermetic Build.

The updates should be reflected by updating
`.github/workflows/hermetic_library_generation.yaml` referenced version
to the current released one.

Author: diegomarquezp

hermetic_build/library_generation/owlbot/templates/java_library/renovate.json

@@ -23,17 +23,6 @@
     ".github/workflows/samples.yaml"
   ],
   "customManagers": [
-    {
-      "customType": "regex",
-      "fileMatch": [
-        "^.kokoro/presubmit/graalvm-native.*.cfg$"
-      ],
-      "matchStrings": [
-        "value: \"gcr.io/cloud-devrel-public-resources/graalvm.*:(?<currentValue>.*?)\""
-      ],
-      "depNameTemplate": "com.google.cloud:sdk-platform-java-config",
-      "datasourceTemplate": "maven"
-    },
     {
       "customType": "regex",
       "fileMatch": [
@@ -107,4 +96,4 @@
   ],
   "semanticCommits": true,
   "dependencyDashboard": true
-}
+}