aotf: replace "reload" with validateReinstall

[oliver-sanders]

• The reload mutation isn't the most helpful command post cylc install.
• Swap it out in the workflow command shortlist for the newly added validateReinstall mutation which has wider scope.

Providing both "reload" and "validate reinstall" as refresh-like options is a bit unclear, so I opted to replace reload (which doesn't serve much function without reinstall) with validate-reinstall. Obvs the reload command is still there for those who need it, but no longer prominently advertised.

Will add a screen recording to the docs and a changes entry there once agreed on this one.

Needs:

• services: validate-reinstall cylc-uiserver#746

Check List

• I have read CONTRIBUTING.md and added my name as a Code Contributor.
• Contains logically grouped changes (else tidy your branch by rebase).
• Does not contain off-topic changes (use other PRs for other changes).
• Applied any dependency changes to both setup.cfg (and conda-environment.yml if present).
• Tests are included (or explain why tests are not needed).
• Changelog entry included if this is a change that can affect users - meh - will add a global changelog though
• Cylc-Doc pull request opened if required at cylc/cylc-doc/pull/XXXX.
• If this is a bug fix, PR should be raised against the relevant ?.?.x branch.

[oliver-sanders]

(drafting this feature until an 8.7.0 aligned milestone)