fix: disable Config Policies apply after updated to empty

[johnkim-det]

Ticket

CM-595

Description

Apply button stays active after submitting empty file. Should become disabled.

Test Plan

In EE, on Config Policies page:
Edit config policies to valid, non-empty content (ex.

constraints:
  resources:
    max_slots: 4

). Then edit to remove all content, and press Apply. At this point, there should be no valid changes to save, so the Apply button should be disabled.

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

[netlify]

✅ Deploy Preview for determined-ui ready!

Name	Link
🔨 Latest commit	45807b9
🔍 Latest deploy log	https://app.netlify.com/sites/determined-ui/deploys/6723b94a0ee8ab00089b5e5f
😎 Deploy Preview	https://deploy-preview-10171--determined-ui.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 50.77%. Comparing base (8c95047) to head (45807b9).
Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10171      +/-   ##
==========================================
- Coverage   54.27%   50.77%   -3.50%     
==========================================
  Files        1259      953     -306     
  Lines      157285   130301   -26984     
  Branches     3644     3642       -2     
==========================================
- Hits        85359    66159   -19200     
+ Misses      71793    64009    -7784     
  Partials      133      133              

Flag	Coverage Δ
harness	?
web	54.30% <100.00%> (ø)

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

Files with missing lines	Coverage Δ
webui/react/src/components/ConfigPolicies.tsx	73.55% <100.00%> (ø)

... and 306 files with indirect coverage changes