Pass pre-install plugins the value of workflow rundir

[wxtim]

Closes #6286

Set options.against_source to the rundir of the workflow, allowing re-install and validate against source to access previous CLI opts as stored in rose-suite-cylc-install.conf

Paired with https://github.com/cylc/cylc-rose/pull/345

Check List

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