feat: expose default URI toggle for Cloud Run v2

[Haihan-Jiang]

Adds a default_uri_disabled input to the v2 module and passes it through to google_cloud_run_v2_service.

The variable defaults to false, so existing module behavior is unchanged unless callers opt in.

Tests:

• generate_docs --per-module-requirements using gcr.io/cloud-foundation-cicd/cft/developer-tools:1.25
• test_lint.sh with DISABLE_TFLINT=1 using the same image; the changed modules/v2 module and v2 examples validated
• test_lint.sh without DISABLE_TFLINT; modules/v2 tflint passed, while examples/v2 tflint crashed under local Docker amd64 emulation
• git diff --check

Refs #229.

[Haihan-Jiang]

This is ready for maintainer review from my side. The remaining terraform-google-cloud-run-int-trigger check appears to require project-side approval/run permissions; could someone take a look or trigger it when convenient?