Motor settings: clean-up/refactor

# Issue Description

As a developer, after https://github.com/isiscomputinggroup/ibex/issues/8427 has been merged I would like to do some refactoring in the `motorExtensions/settings` directory.

Issue 8427 migrated the settings relatively directly from the instruments - which now _allows_ us to do some refactoring work.

### How & Where?

In the `motorExtensions/settings` dir:
- Where directories like `enginx_jaws` have been superceded by `ENGINX/galil/jaws`, delete the former (updating any uses in ioc tests etc)
- Where there is extensive duplication between instruments, pull out common fragments.
- Where files are entirely usused/unneeded/obsolete for a specific instrument, delete them.

### Additional Information

Requires https://github.com/isiscomputinggroup/ibex/issues/8427 to have been merged before starting this.

# Acceptance Criteria
- [ ] Motor settings directory cleaner

# How to Review