NIT-2962: Clean one-off script containers

[pmikolajczyk41]

Previously, after running some scripts, docker space was filled with exited containers. This has been already reported by the docker itself like:

$ ./test-node.bash script send-l2
Using NITRO_CONTRACTS_BRANCH: v3.1.0
Using TOKEN_BRIDGE_BRANCH: v1.2.2
WARN[0000] Found orphan containers ([
  nitro-testnode-scripts-run-ec50076a11b4 
  nitro-testnode-scripts-run-138a9430b88a 
  nitro-testnode-scripts-run-4fa182918ce3 
  nitro-testnode-scripts-run-28cf6eaa8940 
  nitro-testnode-scripts-run-6d8ab3c09c91 
  nitro-testnode-scripts-run-5187961b90db 
  nitro-testnode-scripts-run-205892e27840 
  nitro-testnode-scripts-run-ab7eb9ba0083
]) for this project. If you removed or renamed this service in your compose file, you can run this command with the --remove-orphans flag to clean it up. 

Now we simply remove the script container after it exits.

[Tristan-Wilson]

Good find

[Tristan-Wilson]

I just enabled the option to have auto-merge for this repo, but it doesn't seem like it will get picked up yet for this PR. Assigning back to @pmikolajczyk41 to merge once tests pass.