ci: update workflow paths

[skl]

This PR makes some updates to the CI workflows:

1. Standardise Go version based on go.mod (reduce toil when updating and stay in sync)
2. Add paths to trigger long-running workflows only if necessary (e.g. README changes don't need integration tests)
3. Add more paths to trigger the VM workflow (catch dependent changes)

For example, as this PR touches the workflow files, those workflows are triggered.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 55.42%. Comparing base (3e887d4) to head (a2396e5).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #844   +/-   ##
=======================================
  Coverage   55.42%   55.42%           
=======================================
  Files         251      251           
  Lines       21400    21400           
=======================================
  Hits        11861    11861           
  Misses       8731     8731           
  Partials      808      808           

Flag	Coverage Δ
integration-test	23.24% <ø> (-0.03%)	⬇️
integration-test-arm	0.00% <ø> (ø)
integration-test-vm-${ARCH}-${KERNEL_VERSION}	0.00% <ø> (?)
k8s-integration-test	2.78% <ø> (ø)
oats-test	0.00% <ø> (ø)
unittests	46.53% <ø> (ø)

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[grcevski]

LGTM!