[CI] Migrate 'Inform Incompatible PRs / Check-Compatibility' check to Ubuntu runner

[mx-psi]

The 'Inform Incompatible PRs / Check-Compatibility' check runs on a macOS machine:

opentelemetry-collector/.github/workflows/api-compatibility.yml

Lines 16 to 17 in 92e5423

	Check-Compatibility:
	runs-on: macos-latest

This is inconsistent with the rest of our test suite, that (generally) runs on ubuntu-latest. It also eats into the org's CI minutes: 1 minute in a macOS runner is equivalent to 10 minutes on a Linux runner.

The main (only?) thing to change is this call to mktemp:

opentelemetry-collector/internal/buildscripts/gen-apidiff.sh

Line 45 in a25d438

tmp_dir=$(mktemp -d -t apidiff)

which uses macOS-specific options. Changing this I am able to run this without errors on an Ubuntu machine, but we may want to tackle #7443 first to ensure the targets do not silently fail on Linux because of something else.