ci: remove pangea-3 build

[Bubusch]

• no more official support for Pangea-3
• use Maple instead
• also remove old Pangea-4 host configs

comes with TPL-331

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 58.93%. Comparing base (ebc6ac0) to head (4cf4b5b).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #3923   +/-   ##
========================================
  Coverage    58.93%   58.93%           
========================================
  Files         1351     1351           
  Lines       112834   112834           
========================================
  Hits         66499    66499           
  Misses       46335    46335           

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