Downgrade release 1.8 branch to Go 1.22 in go.mod

[mariomac]

This is required to integrate Beyla 1.8 with Alloy.

The rest of the build and test pipeline still uses Go 1.23

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.95%. Comparing base (632289d) to head (db526fc).

Additional details and impacted files

@@               Coverage Diff               @@
##           release-1.8    #1151      +/-   ##
===============================================
- Coverage        82.06%   81.95%   -0.12%     
===============================================
  Files              140      140              
  Lines            11571    11571              
===============================================
- Hits              9496     9483      -13     
- Misses            1552     1563      +11     
- Partials           523      525       +2     

Flag	Coverage Δ
integration-test	57.30% <ø> (-0.05%)	⬇️
k8s-integration-test	59.00% <ø> (-0.28%)	⬇️
oats-test	36.88% <ø> (ø)
unittests	52.33% <ø> (+0.05%)	⬆️

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