fix: infinite loading spinner on quantity change

[FlorianKe]

A loading spinner will only appear if there is no form validation error

fixes #13917

[github-actions[bot]]

	Warnings
:warning:	The Pull Request doesn't contain any release info, if your changes are relevant for external developers please add an entry to the release info file, including the consequences of the change and how it affects external developers. For detailed infos please refer to the [release documentation guide](https://github.com/shopware/shopware/blob/trunk/delivery-process/documenting-a-release.md).

[explore-openapi[bot]]

OpenAPI Snapshot

Project: shopware/store-api

No changes detected

Your OpenAPI schema is identical to the base branch (trunk).

Links:
All Project Snapshots · Base Branch Snapshot

Project: shopware/admin-api

No changes detected

Your OpenAPI schema is identical to the base branch (trunk).

Links:
All Project Snapshots · Base Branch Snapshot

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 54.06%. Comparing base (5834d59) to head (08c8018). :warning: Report is 6 commits behind head on trunk. :white_check_mark: All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##            trunk   #13930      +/-   ##
==========================================
- Coverage   54.07%   54.06%   -0.01%     
==========================================
  Files        3199     3199              
  Lines       96161    96159       -2     
==========================================
- Hits        51995    51987       -8     
- Misses      44166    44172       +6     

Flag	Coverage Δ
phpunit-migration	94.31% <ø> (ø)
phpunit-unit	51.95% <ø> (-0.01%)	:arrow_down:

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

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

:rocket: New features to boost your workflow:

• :package: JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.