Forcefully remove test container in CI job

because we now use the same container name when launching via the
`docker` command and via `docker-compose` we need to make sure the
container is no more before proceeding to the next step of the test.

Sometimes killing the process may take a bit longer and docker falls on
its face when that happens!

.github/workflows/ci.yml

@@ -54,6 +54,9 @@ jobs:
         run: |
           # this will also kill the parent container
           sudo killall -9 creditcoin-node
+          sleep 10
+          docker rm -f creditcoin-validator
+          sleep 10
 
       - name: Start docker-compose
         run: |