Spire cleanup in CI script

[ionut-arm]

I've tried running the all workflow in the ci.sh script and after an initial failure, trying to rerun resulted in errors related to the spire-server being unable to start, e.g.:

 error="listen tcp 127.0.0.1:8081: bind: address already in use"

Also, the spire-server and a bunch of spire-clients were still running. Some cleanup steps should be introduced to allow rerunning the script.