fix: Update templates for better styling w/o djangocms-admin-style

[fsbraun]

Description

This PR adds the .submit-row <div> used in Django admin for more consistent styling.

It also removes an unused left-over helper function (legacy of pre-2.0):

• djangocms_verisoning.helpers.remove_published_where(qs) used to patch a queryset removing the resulting SQL WHERE statement which restricts the queryset to include published versions only.
• It is not used in the codebase any more. Usage in djangocms-alias has been removed a while ago.
• The official pattern is to use the admin_manager of a versioned model which as the name indicates should only be used in the admin.

Related resources

• #...
• #...

Checklist

• I have opened this pull request against master
• I have added or modified the tests when changing logic
• I have followed the conventional commits guidelines to add meaningful information into the changelog
• I have read the contribution guidelines and I have joined #workgroup-pr-review on
  Slack to find a “pr review buddy” who is going to review my pull request.

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.21% 🎉

Comparison is base (5944cff) 90.69% compared to head (3204c1b) 90.90%.

❗ Current head 3204c1b differs from pull request most recent head bf1c6bf. Consider uploading reports for the commit bf1c6bf to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #352      +/-   ##
==========================================
+ Coverage   90.69%   90.90%   +0.21%     
==========================================
  Files          72       72              
  Lines        2536     2530       -6     
  Branches      357      356       -1     
==========================================
  Hits         2300     2300              
+ Misses        175      170       -5     
+ Partials       61       60       -1     

Files Changed	Coverage Δ
djangocms_versioning/helpers.py	91.11% <100.00%> (-0.29%)	⬇️

... and 1 file with indirect coverage changes

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