kpvs: fix naming and inconsistencies

- Tweak ThrustAsymmetryWithThrustReversersDeployed{Duration,Max}:
  - Make consistent: Check for when thrust reversers are not 'Stowed'.
- Removed old version of duplicate KPV.
- Updated names to match naming convention.
- Unit test fixes.
- Added units to the KPV definitions.
- General tidying up of relevant nodes and test cases.
  - Strip excess docstring placeholders.