fix: prevent full iframe reload after xblock edition

[bra-i-am]

Description

This PR addresses an issue that causes a full iframe reload after saving edited xblock data. To prevent the page reload, these changes remove the entire iframe reload, which was part of a previous implementation to display the Publish button after editing an xblock. However, this PR uses a different approach to achieve that.

Supporting information

This PR fixes point 1 in the issue #1893

Testing instructions

Before	After
Screencast from 04-07-25 12:01:53.webm	Screencast from 04-07-25 11:59:48.webm

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[codecov]

Codecov Report

Attention: Patch coverage is 20.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 94.17%. Comparing base (ad62519) to head (7cc6c1f).
Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
src/course-unit/data/slice.js	0.00%	3 Missing ⚠️
src/course-unit/hooks.jsx	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2257      +/-   ##
==========================================
- Coverage   94.17%   94.17%   -0.01%     
==========================================
  Files        1167     1167              
  Lines       24678    24677       -1     
  Branches     5271     5272       +1     
==========================================
- Hits        23241    23239       -2     
- Misses       1369     1370       +1     
  Partials       68       68              

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