Remove explicit VOLUME creation in dockerfile

Nobody has claimed this yet.

Current `dockerfile` contains:

https://github.com/matomo-org/docker/blob/adb618afe1527cfed9655983fe79a6275b65ad1b/apache/Dockerfile#L96-L98

On `docker run` this creates anonymous volumes that are not clearly visible.

What is problematic is that the entrypoint script checks whether anything is already on that hidden volume:
https://github.com/matomo-org/docker/blob/adb618afe1527cfed9655983fe79a6275b65ad1b/apache/docker-entrypoint.sh#L33

And if not, then extracts the sourcecode:
https://github.com/matomo-org/docker/blob/adb618afe1527cfed9655983fe79a6275b65ad1b/apache/docker-entrypoint.sh#L55

Besides the fact that this extraction is additive (i.e. not a sync) and can leave old files lingering there, the even more problematic issue is that if one upgrades the Matomo image version in the deployment `dockerfile` the new container may or may not (depending on how it is run) reuse the hidden volume and not update Matomo. Hence you may expect to see Matomo v5 based on the new image, but you see your old v4 still at runtime.

If someone wants to use a volume, this should be specified in `docker run` or in the compose file like here:
https://github.com/matomo-org/docker/blob/adb618afe1527cfed9655983fe79a6275b65ad1b/.examples/apache/compose.yml#L24

Hence I believe VOLUME should be a runtime option, not a hidden side-effect of the baseline image.

Start with apache/Dockerfile lines 96-98 and compare the runtime behavior with apache/docker-entrypoint.sh lines 33 and 55. Review the .examples/apache/compose.yml volume configuration, then verify that the baseline image no longer creates an implicit volume and that explicit volume use remains available through runtime configuration.

Written by the indexing model from the issue text.