Improve init wps script

[nbrinckm]

Still work-in-progress

• use the correct env variable for the base url of the geoserver (tried to send to the wps before that change)
• remove the volume for the hsql data for the wps config (should be set via env variables & the init script instead).
• wait until the geoserver accepts the requests with the updated password (in case there is a password change)
• add handling to be able to update the wps password without docker-compose down (stores the password for the wps within the container)