Remove PT_qbid_limit_switch parameter and it's assocated False code

[martinholmer]

Fixes #2822 confusion without any restriction on ability to specify a PT_qbid_limit_switch==False reform (as discussed here).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.42%. Comparing base (af96206) to head (9ecf038).
Report is 13 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2823   +/-   ##
=======================================
  Coverage   99.42%   99.42%           
=======================================
  Files          13       13           
  Lines        2613     2613           
=======================================
  Hits         2598     2598           
  Misses         15       15           

Flag	Coverage Δ
unittests	99.42% <ø> (ø)

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