Ensure autosave on layoutset switch is done for correct layoutset.

[nkylstad]

Description

Seems like the issue was caused by the setup in FormItemContext.
There was an autosave set up for the "previous" layout/layoutset when changing layoutset. This was triggered when switching layoutsets, but the save was done for the newly selected layoutset, with context from the old layoutset.

Related Issue(s)

• Mixed data between layoutsets #12497

Verification

• Your code builds clean without any errors or warnings
• Manual testing done (required)
• Relevant automated test added (if you find this hard, leave it and we'll help out)

Documentation

• User documentation is updated with a separate linked PR in altinn-studio-docs. (if applicable)

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 90.17%. Comparing base (beed659) to head (9f1dc92).
Report is 10 commits behind head on main.

Files	Patch %	Lines
...kages/ux-editor/src/containers/FormItemContext.tsx	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #12703   +/-   ##
=======================================
  Coverage   90.17%   90.17%           
=======================================
  Files        1296     1296           
  Lines       18557    18557           
  Branches     2261     2261           
=======================================
  Hits        16733    16733           
  Misses       1564     1564           
  Partials      260      260           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.