chore: Build all modules of sdk-platform-java in hermetic generation workflow. (#2864)

This is to fix the issue in
https://github.com/googleapis/sdk-platform-java/actions/runs/9418294714/job/25945455263?pr=2860.

---------

Co-authored-by: cloud-java-bot <[email protected]>

Author: blakeli0

.github/workflows/hermetic_library_generation.yaml

@@ -37,7 +37,7 @@ jobs:
     - name: Install gapic-generator-java-pom-parent
       shell: bash
       run: |
-        mvn clean install -pl gapic-generator-java-pom-parent
+        mvn -V -B -ntp clean install -DskipTests
     - name: Generate changed libraries
       shell: bash
       run: |