[test] Remove PrgEnv-cray_classic from Dom and add it to Daint

[vkarak]

• The classic CCE compiler and the corresponding modules are removed for CCE 10, which is the default in CDT 20.06, so this PR removes the corresponding environment on Dom.
• Similarly we add this classic CCE environment on Daint, since it has been forgotten.

Fixes UES-927.

[victorusu]

lgtm

[codecov-commenter]

Codecov Report

Merging #1388 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1388   +/-   ##
=======================================
  Coverage   91.75%   91.75%           
=======================================
  Files          83       83           
  Lines       12712    12712           
=======================================
  Hits        11664    11664           
  Misses       1048     1048           

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