Tests in CI have sporadic and intermittent failures

[JeffersonBledsoe]

The CI runs for the tests will occasionally fail with the following error:

AssertionError: UnexpectedAlertPresentException: Alert Text: {Alert text : 
Message: unexpected alert open: {Alert text : }
  (Session info: chrome=93.0.4577.63)

For an example, see this run on the main branch, where the PR's tests all passed, but the merge commit failed with this message.

Reading through the log of the failed runs (Failed run for 5.1 example, Failed run for 5.2 example) it seems that this occurs when trying to save the mosaic page and so it's likely we're missing a wait somewhere.