Spanner integration tests take hours

[meltsufin]

Example: https://github.com/GoogleCloudPlatform/spring-cloud-gcp/actions/runs/5657994047/job/15328318471

This is slowing us down.

@prash-mi Is this something you can investigate?

[suztomo]

Memo:

As per Mike, sometimes the job finishes in 15 mins.