[Bug] Fix tests for `test_google_sheets`

[anzelpwj]

Detailed Description

There are some fixes we need to make to https://github.com/move-coop/parsons/blob/main/test/test_google/test_google_sheets.py. Specifically:

• tearDown is commented out - I presume we should re-enable it.
• Add a few strategic time.sleep calls so that you don't hit the rate limit.
  • Longer term maybe we want to look at https://docs.gspread.org/en/v6.0.0/api/http_client.html#gspread.BackOffHTTPClient ?
• test_read_worksheet and test_read_sheet read from fixed worksheets that many folks will not have access to. Can we have this point to the spreadsheet we make in setUp instead?
• test_append_to_spreadsheet literally says "BROKEN TEST", we should fix.