Investigate using materialized view(s) for the feature search query

[jcscottiii]

During a recent round of database optimizations, Jason had a good idea to leverage materialized views for the feature search query.

See this comment for background: https://github.com/GoogleChrome/webstatus.dev/pull/103#discussion_r1528957158

Whoever does this should:

• [ ] Evaluate the performance (it should help)
• [ ] Evaluate how the developers can verify this without impacting the main staging and prod versions
  • This can be through having developers use the GCP Spanner free tier since the emulator does not currently support materialized views. Doing this should include instructions for developers. Also, it should include a way the CI can assert tests that do this. This could be similar to the cloud tests in WPT.fyi that run on actual GCP instances in the GitHub actions pipeline.