task: change expired icon

[oliver-sanders]

Small proposal as a PR for consideration sometime after 8.3.0 release.

The task expired icon isn't the most obvious and could be a little better:

• Filled shapes are used for "finished" states (succeeded & failed), empty shapes are used for "non finished" states (waiting, preparing, submitted, submit-failed). Due to the nature of expiry, a non-finished state is more appropriate.
• The meaning of the clockface isn't especially obvious, especially as tasks in an expired state may now be the result of manual user intervention.

Before:

After:

This also uses fewer SVG elements which should make it more efficient (note the expired styling is only applied for expired icons).

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] CHANGES.md 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.

[oliver-sanders]

Will come back to this later.