Switch Actions organization from ecmwf-actions to ecmwf

[recmanj]

Update CI/CD workflows as ecmwf-actions actions have been moved to ecmwf organization.

[FussyDuck]

All committers have signed the CLA.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 48.96%. Comparing base (0f3621b) to head (5a04723).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #166      +/-   ##
===========================================
+ Coverage    48.94%   48.96%   +0.01%     
===========================================
  Files         1189     1189              
  Lines        98454    98454              
  Branches     14750    14750              
===========================================
+ Hits         48193    48204      +11     
+ Misses       50261    50250      -11     

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