Switch to custom fcrepo container image
This uses:
- the latest release 4.7.6 from fcrepo's 4.7 version branch
- the latest Tomcat 9 release that still supports Java 8
The previous image "ghcr.io/samvera/fcrepo4:4.7.5" has never actually worked, so this new image restores compatibility with the original "ualbertalib/docker-fcrepo4:4.7" image.
Also remove unneeded variables from .env.template and .env.template.development.
Fixes: a6a58dcd "Upgrade fedora image in docker" Fixes: #19 (moved) Fixes: FDM/rdm-system/antleaf-projectmanagement#216
Note: This should only be merged after Update docker-entrypoint.sh: Fix curl calls in ... (!285 - merged).
We have tested this on our rdms-dev
instance, and haven't found any issues.