ci: Run scheduled e2e tests on weekdays at 01:00 UTC

[vdusek]

Summary

Adjusts the scheduled e2e tests workflow:

• Runs only on weekdays (Mon–Fri) instead of every day — avoids weekend failures with no one around to triage.
• Triggers at 01:00 UTC (was 06:00 UTC) so results are ready before the workday starts in Europe.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.88%. Comparing base (a7598f0) to head (ed24d78).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1903      +/-   ##
==========================================
+ Coverage   92.86%   92.88%   +0.01%     
==========================================
  Files         167      167              
  Lines       11709    11709              
==========================================
+ Hits        10874    10876       +2     
+ Misses        835      833       -2     

Flag	Coverage Δ
unit	92.88% <ø> (+0.01%)	⬆️

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