exp: support dvc-task/celery message cleanup

[pmrowla]

• ❗ I have followed the Contributing to DVC checklist.

• 📖 If this PR requires documentation updates, I have created a separate PR (or issue, at least) in dvc.org and linked it here.

Thank you for the contribution - we'll try to review it as soon as possible. 🙏

Closes: #8676
Related: #8787

• Adds dvc exp clean to cleanup unneeded files from .dvc/tmp/exps. Currently only does dvc-task/celery garbage collection
• Celery messages are now automatically garbage collected in the background on queue worker exit (when a complete dvc queue start or dvc exp run --run-all batch finishes)

[codecov]

Codecov Report

Patch coverage: 97.43% and project coverage change: -0.01 ⚠️

Comparison is base (286f4fd) 92.97% compared to head (e5edf0c) 92.96%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9090      +/-   ##
==========================================
- Coverage   92.97%   92.96%   -0.01%     
==========================================
  Files         459      461       +2     
  Lines       37113    37150      +37     
  Branches     5369     5370       +1     
==========================================
+ Hits        34504    34535      +31     
- Misses       2082     2085       +3     
- Partials      527      530       +3     

Impacted Files	Coverage Δ
dvc/commands/experiments/__init__.py	100.00% <ø> (ø)
dvc/repo/experiments/queue/celery.py	85.66% <66.66%> (-2.12%)	⬇️
dvc/commands/experiments/clean.py	100.00% <100.00%> (ø)
dvc/commands/experiments/queue_worker.py	100.00% <100.00%> (ø)
dvc/repo/experiments/__init__.py	87.23% <100.00%> (+0.13%)	⬆️
dvc/repo/experiments/clean.py	100.00% <100.00%> (ø)
tests/func/experiments/test_experiments.py	100.00% <100.00%> (ø)
tests/unit/command/test_experiments.py	99.60% <100.00%> (+0.01%)	⬆️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.