It was disabled to avoid malicious usage but with the monitoring in
place and the demo account restricted to limited resources, it's
probably safe to try enabling this again.

For legitimate users, not having the terminal is pretty annoying.
Should not penalize legit users for some rogue users.

This was not possible before since non-empty dir deletion was not possible.

The container died instantly on creation startup.

Fix this error found during autodeploy:
```
fix GeoServer data dir permission on first run only, when data dir do not exist yet.
+ DATA_DIR='${DATA_PERSIST_ROOT}/geoserver'
+ '[' -n  ]
+ docker run --rm --name fix-geoserver-data-dir-perm --volume '${DATA_PERSIST_ROOT}/geoserver:/datadir' --env FIRST_RUN_ONLY bash:5.1.4 bash -xc 'if [ -z "$FIRST_RUN_ONLY" -o ! -f /datadir/global.xml ]; \
    then chown -R 1000:10001 /datadir; else echo "No execute."; fi'
docker: Error response from daemon: create ${DATA_PERSIST_ROOT}/geoserver: "${DATA_PERSIST_ROOT}/geoserver" includes invalid characters for a local volume name, only "[a-zA-Z0-9][a-zA-Z0-9_.-]" are allowed. If you intended to pass a host directory, use absolute path.
See 'docker run --help'.
```

…lways read last

env.local will always have the latest updated values so no need for
delayed eval.

This reverts commit 6687185.

To be implemented better in a different PR.

Francis proposed to centralize all the sourcing logic of default.env and
env.local and calling process_delayed_eval in a same file so all scripts
to not have to remember the loading sequence and we have a central
location to update that loading sequence without having to edit all the
scripts in the future.