Remove unneeded helpers, use kubectl waiters, set bash strict mode

[simonmarty]

Issue #, if available:

Description of changes:

• wait_for_process isn't needed as far as I can tell. We can do all the waiting we need using kubectl's wait command.
• Set bash strict mode to exit non-zero on subcommand failure. This ensures we exit non-zero on a failing bats test.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.10%. Comparing base (6dbe3b9) to head (65203a6).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #545   +/-   ##
=======================================
  Coverage   60.10%   60.10%           
=======================================
  Files          11       11           
  Lines         762      762           
=======================================
  Hits          458      458           
  Misses        287      287           
  Partials       17       17           

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[reyhankoyun]

Could we add these variables back in? I think these are needed by wait_for_process helper function.

[simonmarty]

Ah, this made me realize I can't strip out wait_for_process because it's being used by the aws.bats file used by the upstream driver end to end tests, putting those back in.

The two env vars can be stripped out though, the usage of these helpers has been removed.

[ThirdEyeSqueegee]

The driver doesn't actually use our aws.bats file, theirs diverged a while ago. I removed aws.bats and the rest of the old testing setup in #541