flake: cli TestServer/BuiltinPostgres periodically fails to download from maven

[johnstcn]

Seen here:

https://github.com/coder/coder/actions/runs/14352487225

=== FAIL: cli TestServer/BuiltinPostgres (180.00s)
    clitest.go:75: invoking command: coder --global-config /tmp/TestServerBuiltinPostgres4130513051/002 server --http-address :0 --access-url http://example.com/ --cache-dir /tmp/TestServerBuiltinPostgres4130513051/001
    t.go:106: 2025-04-09 08:41:58.212 [info]  cli: stdout: Started HTTP listener at http://[::]:43763
    t.go:106: 2025-04-09 08:41:58.212 [info]  cli: stdout: Using built-in PostgreSQL (/tmp/TestServerBuiltinPostgres4130513051/002/postgres)
    clitest.go:261: command "coder server" exited with error: running command "coder server": Failed to start built-in PostgreSQL. Optionally, specify an external deployment with `--postgres-url`:
            github.com/coder/coder/v2/cli.startBuiltinPostgres
                /home/runner/work/coder/coder/cli/server.go:2175
          - unable to connect to https://repo1.maven.org/maven2

[johnstcn]

One possible option is to allow overriding BinaryRepositoryURL to a known location in tests.

https://pkg.go.dev/github.com/fergusstrange/embedded-postgres#Config.BinaryRepositoryURL

The catch is that it needs to be available under a specific path:

		jarDownloadURL := fmt.Sprintf("%s/io/zonky/test/postgres/embedded-postgres-binaries-%s-%s/%s/embedded-postgres-binaries-%s-%s-%s.jar",
			remoteFetchHost,
			operatingSystem,
			architecture,
			version,
			operatingSystem,
			architecture,
			version)

[johnstcn]

@ibetitsmike suggests using an alternative Maven mirror e.g. https://repo.maven.apache.org/maven2

[johnstcn]

Another option could be to allow setting the embedded-postgres BinaryPath and then caching that folder in GH actions.

[johnstcn]

We have recently migrated from Google Container Registry to Google Artifact Registry for our container images. Given that this is a currently extant dependency, we can simply vendor the embedded-postgres binary in a GCS bucket.