fix: add watcher for job and avoid unnecessary reconcile

[Fei-Guo]

This PR addresses two problems:

1. We should add watcher for tunning jobs. Otherwise, if a tunning job is deleted before it is done, the controller will not recreate it.
2. Currently, the gpu-provisioner will update the machine object with heartbeat information every two minutes. This will trigger a workspace reconcile. In practice, if the machine keeps in the ready state, we don't need to reconcile the workspace. Add an additional machine event filter to avoid unnecessary reconciles.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.

Project coverage is 60.57%. Comparing base (ed546f0) to head (c109f58).
Report is 10 commits behind head on main.

Files	Patch %	Lines
pkg/controllers/workspace_controller.go	0.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #527      +/-   ##
==========================================
- Coverage   61.10%   60.57%   -0.54%     
==========================================
  Files          29       30       +1     
  Lines        2602     2625      +23     
==========================================
  Hits         1590     1590              
- Misses        921      944      +23     
  Partials       91       91              

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