cylc-ui Graph grouping/collapsing code tidy

Follow-up to #1810 Partly addresses #1130

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] Tests are updated
[x] Changelog entry not needed
[x] No docs needed
[x] If this is a bug fix, PR should be raised against the relevant ?.?.x branch.

Apr 07 '25 11:04 MetRonnie

LGTM, but doesn't work right.

I tested with the complex workflow, the graph didn't produce any errors, but it also didn't layout and left all of the tasks in a long line.

When I tried to group by cycle I got this error in the console:

TypeError: this.allParentLookUp[l] is undefined

Apr 08 '25 15:04 oliver-sanders

As discussed in person, I can't reproduce the problem with the same workflow

Apr 11 '25 11:04 MetRonnie

I tested with the complex workflow, the graph didn't produce any errors, but it also didn't layout and left all of the tasks in a long line.

I wasn't able to replicate this.

May 02 '25 14:05 wxtim

Sorry for the delay.

The error was very persistent, I finally managed to get past it by:

:sweat:

Don't understand this, but it's working for me now...

May 13 '25 12:05 oliver-sanders