Revert PR 11966 to fix errors when interacting with edit fields in MS Excel

[lukaszgo1]

This is opened against beta.

Link to issue number:

Work around for issue #12402

Summary of the issue:

PR #11966 started using DisplayModelEditableText for edit fields with empty window text to improve access to IDE's by MCS Electronic - this unfortunately broke access to some edit fields in Excel as they were forcibly using DisplayModelEditableText and now they were getting this class twice in the MRO. When trying to come up with a fix I've found another problems with the approach from #11966 namely edit fields which require UnidentifiedEdit weren't getting it in the MRO when they are initially empty.

Description of how this pull request fixes the issue:

Since we're quite close to the release it makes sense to revert #11966 for now and investigate another approach - the program for which the original fix was needed is quite niche and therefore I don't consider this to be a big loss. I'll try to come up with something better for the next release.

Testing strategy:

Asked reporter from #12402 to test - they have confirmed that the problem no longer occurs.

Known issues with pull request:

• Edit fields in IDE's by MCS Electronic are not accessible.

Change log entries:

I've removed entry from #11966 as part of this PR.

Code Review Checklist:

• Pull Request description is up to date.
• Unit tests.
• System (end to end) tests.
• Manual tests.
• User Documentation.
• Change log entry.
• Context sensitive help for GUI changes.

Linting failure is expected here as this just reverts the commit.

[AppVeyorBot]

• PR introduces Flake8 errors
• Build (for testing PR)

See test results for failed build of commit 3c97a226f5

[seanbudd]

@michaelDCurran @feerrenrut I've added you as reviewers as I won't be able to merge this with the lint check fail.