Fixed output messages for CMOR logging

[schlunma]

Description

Fixes log formatting of CMOR messages.

Closes #1492

Checklist

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[codecov]

Codecov Report

Merging #1494 (f8bfd5a) into main (4fb6b79) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1494   +/-   ##
=======================================
  Coverage   90.71%   90.71%           
=======================================
  Files         197      197           
  Lines       10517    10517           
=======================================
  Hits         9541     9541           
  Misses        976      976           

Impacted Files	Coverage Δ
esmvalcore/cmor/check.py	97.73% <ø> (ø)

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[valeriupredoi]

this is to my heart - proper detail oriented 😁 Thanks, Manu!