Install script INSTALL_K3S_PR support does not work if CI has run more than once

[brandond]

If the action runs multiple times (say due to being restarted to address a flake), the RUN_ID expression may return multiple results:

k3s/install.sh

Lines 496 to 497 in 1d22b69

	# Extract the Run ID from the build workflow and lookup artifacts associated with the run
	RUN_ID=$(echo "$build_workflow" | jq -r ' .details_url' | awk -F'/' '{print $(NF-2)}')

#8 1.395 + RUN_ID='9118227575
#8 1.395 9118227594'
#8 1.396 ++ curl -s -H 'Authorization: Bearer xxx' 'https://api.github.com/repos/k3s-io/k3s/actions/runs/9118227575
#8 1.396 9118227594/artifacts'
#8 1.402 + artifacts=

[brandond]

cc @dereknola

[brandond]

no backports, since install script changes only go to master