kgap-graphdb needs a health status

[marc-portier]

we should add a health-check monitor for the kgap-graphdb service [1], [1bis]

this will allow:

• for compose-setups to wait for this service to be available before spinning up themselves (e.g. sembench operations will depend on it) [2]
• testing environments that use it to have wait for the spin-up [3]

[1] https://scoutapm.com/blog/how-to-use-docker-healthcheck [1bis] https://lumigo.io/container-monitoring/docker-health-check-a-practical-guide/ [2] https://www.warp.dev/terminus/docker-compose-depends-on [3] https://stackoverflow.com/questions/21183088/how-can-i-wait-for-a-docker-container-to-be-up-and-running