E2E test stabilization, and upgrade to latest Cypress v9 and axe-core

[tdonohue]

Description

Simple PR to attempt to stabilize some randomly failing e2e tests. Based on what I've seen in recent CI runs, it looks like there are three main random failures:

• Random authentication errors (sometimes the auth fails... I've attempted to fix this in this PR)
• Random accessibility testing failures (Not sure our code is at fault. Appears to be a possible bug in Cypress or Axe. So, I upgraded to latest axe-core and cypress to see if that helps)
• Random page not loading failures. Uncertain of the root cause at this time. May be a Cypress issue?

This PR does the following:

• Upgrade us to the latest version of Cypress v9 and axe-core.
  • (NOTE: Cypress v10 is also now available, but that's a major upgrade requiring refactoring of existing e2e tests. So, that may require much more work to complete & may need to be scheduled for a future date.)
• Change our authentication strategy in e2e tests to use the login form in the UI. Previously we were using requests directly to the backend REST API to authenticate -- while that approach is likely faster, it seems to sometimes hit random failures (possibly cause of an out-of-sync CSRF token?). It's likely more stable to use our login form at all times.

Instructions for Reviewers

• Verify e2e tests pass & seem more stable.
• Check code.

[tdonohue]

This is ready for review now. While it hasn't fully stabilized all tests (After restarting tests 5 times, I did finally hit some random Axe accessibility check failures), it seems better than previously.

[tdonohue]

@artlowel : This might be one you could quickly review. From what I've seen, these small changes make the e2e tests more stable, but there still will be some random failures (they seem less frequent though)

[atarix83]

thanks @tdonohue

it seems to be better, but we can't be 100% sure it resolves the random errors definitely.
I think we need to keep monitored for upcoming builds after the merge and plan to migrate to new cypress v10

[tdonohue]

Agreed @atarix83. I don't think this is going to fix the random failures 100% of the time, but I find the random failures are less frequent with this PR in place. I also agree that an upgrade to Cypress v10 is needed at some point...however, that's a major upgrade (I attempted it locally & found it to be quite complex & wasn't able to get it working properly -- I think v10 still is a bit buggy).

In any case, merging this immediately & we'll see if this has a decent impact or if we need to prioritize a Cypress v10 upgrade sooner.