chore(ci): move to ubuntu-26.04

[mayeut]

Now that ubuntu-26.04 is GA, let's use it everywhere - almost.
The only jobs left on ubuntu-24.04 are:

• x86_64 coverage in order for SDE to be able to run properly (we can't test anything less than x86_64-v3 otherwise)..
• benchmark while waiting for CodSpeed support

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.58%. Comparing base (82a4c6f) to head (1a1ea90).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1072   +/-   ##
=======================================
  Coverage   99.58%   99.58%           
=======================================
  Files          11       11           
  Lines        1937     1937           
  Branches      306      306           
=======================================
  Hits         1929     1929           
  Partials        8        8           

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[codspeed]

Merging this PR will not alter performance

✅ 48 untouched benchmarks

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_{Comparing ubuntu-26.04 (1a1ea90) with master (82a4c6f)}

[mayeut]

blocked by actions/runner-images#14790