Inconsistent handling of env vars

[nutjob4life]

The variable ZEO_SHARED_BLOB_DIR can be set to on if the ZEO server and the instance have access to the same directory; defaults to off ✅

But the variable ZEO_PACK_KEEP_OLD must be set to false, no, 0, n, or f to disable the pack to keep the old db. Setting it to off doesn't do it ❌

It'd sure be nice if these two boolean environment variables treated boolean values the same 😬

[avoinea]

@nutjob4life Indeed:

We have:

https://github.com/plone/plone.docker/blob/a516871e08532c8a343f9e9e713c8abc8d80aae6/5.2/5.2.4/debian/docker-initialize.py#L83

while:

https://github.com/plone/plone.docker/blob/a516871e08532c8a343f9e9e713c8abc8d80aae6/5.2/5.2.4/debian/docker-initialize.py#L40

A PR would be appreciated :wink: