ci: update patterns to include postgres tools and mcp test harness

[anubhav756]

This PR updates the PATTERN regex in .ci/integration.cloudbuild.yaml for all Postgres-related test shards (cloud-sql-pg, alloydb, alloydb-pg, alloydb-omni, and postgres).

The patterns now include internal/tools/postgres and tests/mcp_tool.go. This ensures that changes to Postgres tools or the new MCP test harness will correctly trigger the relevant integration tests in the CI pipeline. Previously, modifications to these directories would not trigger tests unless other shared files were also modified.

[github-actions]

🧨 Preview deployments removed.

Cloudflare Pages environments for pr-2988 have been deleted.

[gemini-code-assist]

Code Review

This pull request updates the Google Cloud Build CI configuration by adding internal/tools/postgres and tests/mcp_tool.go to the change detection patterns for various Postgres-related integration test shards. Feedback was provided to also include tests/tool.go in the AlloyDB test pattern to ensure that changes to shared test utilities correctly trigger the integration tests, as tests/mcp_tool.go depends on helper functions within that file.

[gemini-code-assist]

For consistency with other Postgres-related test shards and to correctly handle dependencies, it's a good idea to also include tests/tool.go in this pattern.

The new test harness tests/mcp_tool.go uses helper functions from tests/tool.go (like RunRequest). Without including tests/tool.go in the pattern, changes to this shared test utility file won't trigger the alloydb integration tests, which could lead to missed regressions.

        PATTERN="alloydb|internal/sources/postgres|internal/tools/postgres|tests/postgres|internal/server/|tests/common.go|tests/tool.go|tests/mcp_tool.go|.ci/"