fix: Add on delete cascade to system_metrics

[gt2345]

Ticket

MD-530

Description

Fix an issue preventing deleting experiment with profiling enabled.

Test Plan

Create an experiment with profiling, one example is to change determined/examples/tutorials/mnist_pytorch/train.py to add profiling_enabled:

trainer.fit(max_length=max_length, latest_checkpoint=latest_checkpoint, profiling_enabled=True)

Verify that "Profiler" tab for that experiment in the Web UI exists with value.
Delete the experiment, the experiment should eventually disappear with no error.

Checklist

• Changes have been manually QA'd
• New features have been approved by the corresponding PM
• User-facing API changes have the "User-facing API Change" label
• Release notes have been added as a separate file under docs/release-notes/
  See Release Note for details.
• Licenses have been included for new code which was copied and/or modified from any external code

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 54.47%. Comparing base (e7186fe) to head (c663340).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10113      +/-   ##
==========================================
- Coverage   54.47%   54.47%   -0.01%     
==========================================
  Files        1267     1267              
  Lines      159439   159439              
  Branches     3637     3638       +1     
==========================================
- Hits        86854    86851       -3     
- Misses      72452    72455       +3     
  Partials      133      133              

Flag	Coverage Δ
backend	45.66% <ø> (-0.01%)	⬇️
harness	72.55% <ø> (ø)
web	54.02% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

see 4 files with indirect coverage changes

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[azhou-determined]

nice! 🔥