ci(multiarch): improve build times

[andrewazores]

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See #373
Based on #580

Description of the change:

This change allows an environment variable to be configured so that...

Motivation for the change:

This change is helpful because users may want to...

How to manually test:

1. Run CRYOSTAT_IMAGE=quay.io... bash smoketest.bash...
2. ...

[andrewazores]

In the end, these efforts haven't really helped the build time. This is just trying to add caching, but the caches are not easily preserved between runs, so nothing changes.

[andrewazores]

The last commit should preserve the src/main/webui/.build_cache, which might actually help. I hope so, anyway. On my machine a fresh web-client build (npm deps installed but build cache deleted) takes ~12.5 seconds, whereas a rebuild takes ~2 seconds - probably because it's just spending time verifying things against the cache.

[github-actions]

This PR/issue depends on:

• ci(runner): use ubuntu 24.04 runner, ensure podman 4 from repo installed, use localstack:stable #580
  By Dependent Issues (🤖). Happy coding!

[andrewazores]

/build_test

[github-actions]

Workflow started at 7/25/2024, 11:07:45 AM. View Actions Run.

[github-actions]

No OpenAPI schema changes detected.

[github-actions]

No GraphQL schema changes detected.

[github-actions]

CI build and push: All tests pass ✅ (JDK17)
https://github.com/cryostatio/cryostat/actions/runs/10096652182

[mwangggg]

oh actually, it might be nice to update the actions to versions that use node20 so there aren't so many deprecation warnings.

[mwangggg]

looks good now