Classic Editor tests disabled until we update to edit existing classic post

[cameronvoell]

Summary

The Classic (Aztec) editor is being deprecated for creating new posts in WPAndroid. See simple sites classic editor deprecation for new posts PR here: #14381. Atomic, and self-hosted blogs are planned to happen afterwards.

Since users will still be able to edit existing posts, existing classic editor tests should be updated to edit an existing classic post, instead of creating a new one.

While this work is pending, classic editor tests are disabled.

Update: We decided in p9ugOq-20E-p2#comment-4395 to re-enable the classic tests to help prevent any future classic editor regressions. We'll only re-enable the simplest test, testPublishSimplePost, since we only want a minimal test in place.

[guarani]

I updated the issue based on a new decision: we'll re-enable a single classic editor test.