[frontend] Remove feature flag for bulk entities (#4352)

[lndrtrbn]

Proposed changes

• Remove feature flag BULK_ENTITIES

Related issues

• Bulk entity creation of SDO/SCO with Copy/Pasting #4352

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality
• I wrote test cases for the relevant uses case (coverage and e2e)
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.21%. Comparing base (79d21ee) to head (e30a37b).
Report is 5 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #8229   +/-   ##
=======================================
  Coverage   66.20%   66.21%           
=======================================
  Files         597      597           
  Lines       60341    60341           
  Branches     6203     6205    +2     
=======================================
+ Hits        39951    39956    +5     
+ Misses      20390    20385    -5     

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