ci: gate go/java/python tool caches to github-hosted runners (#12001)

Follow-up to #11985/#11986: setup-go/setup-java/setup-python steps
added or restructured since (e.g. by #11981's shared-artifact layout)
were missed. On self-hosted runners setup-go restores/saves a ~5GB
module cache archive per job — pure waste when the module cache is
already on local disk — and the restore blocks the job for minutes.

.github/workflows/java_unit_tests.yml

@@ -34,7 +34,7 @@ jobs:
         with:
           java-version: ${{ matrix.java }}
           distribution: 'temurin'
-          cache: 'maven'
+          cache: ${{ runner.environment == 'github-hosted' && 'maven' || '' }}
       
       - name: Build and Install SeaweedFS Client
         working-directory: other/java/client