feat!: reorganize installation testing TF + add builds

[ace-n]

• Added a data.tf file, and moved the google_project resource there
• Added Cloud Build triggers for Delivery Image building (presubmit) and Installation Testing (nightly).
• Renamed the (mostly IAM resource-based) delivery_testing.tf file to iam.tf

✅ I've tested this, and all triggers are passing.

[grayside]

This generally seems good, but want to check: are we using the same pub/sub topic for both nightly system and deployment tests? Are there any shared resources that could end up in contention?

[ace-n]

The website system tests are not currently running nightly; rather, they run against localhost upon presubmit.

That said, building and testing resources on the same topic can cause race conditions (primarily, using the previous day's artifacts in test runs).

I'd argue that we should consider address the race condition issue in a follow-on PR by creating two separate topics - nightly_builds and nightly_tests, where the latter runs ~1 hour after the former.

Note: I'm not 100% sure I'll get to that tomorrow, so if it's a blocker perhaps you and Charlie / Patti could pair on it? I'm also happy to take a "first stab" and let one of y'all get it over the finish line.

[grayside]

Let's explore that as a follow-up design discussion. For now it sounds like this is not a source of conflicts.

[ace-n]

@grayside filed as #533