fix(studio): enforce Google ADK floor for managed Sidecar

[zyn080302]

Summary

• Replace inherited bare or outdated google-adk requirements when staging managed Harness Sidecar builds.
• Enforce google-adk>=1.34.0 so the current VeADK source can import SkillToolset.
• Keep ordinary non-Sidecar installation and runtime paths unchanged.

Root cause

The managed base image already contains an older Google ADK version. A bare google-adk requirement was therefore considered satisfied, so the application build did not upgrade it. The Runtime then failed during startup because google.adk.tools.skill_toolset was unavailable.

Verification

• tests/cli/test_managed_sidecar_source.py: 7 passed
• tests/cli/test_studio_rbac.py: 84 passed
• Ruff check/format, hardcoded-secret pre-commit, and git diff --check passed
• Built wheel verified to contain and use the google-adk>=1.34.0 rewrite logic