remove DriverSettingsMixin alias for AutoSettingsMixin

[seanbudd]

Link to issue number:

Part of #12123

Implements deprecation announced in: e8f8a89

Summary of the issue:

gui.DriverSettingsMixin was deprecated a year ago

Description of how this pull request fixes the issue:

gui.DriverSettingsMixin is removed in favour of the equivalent alias gui.AutoSettingsMixin

Testing strategy:

Search the code base for usages of DriverSettingsMixin and confirm there is none

find . -type f -name '*.py' -exec grep -P "DriverSettingsMixin" {} +

General user testing in the alpha/beta stages will confirm lack of changes

Known issues with pull request:

None

Change log entry:

Developer Changes

-`gui.DriverSettingsMixin` has been removed - use `gui.AutoSettingsMixin` (#12144)

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.