Show active instead of clients-ever-seen on the dashboard

[DL6ER]

What does this implement/fix?

Show active clients instead of clients-ever-seen on the dashboard:

When the two numbers are different, show both

This PR depends on the corresponding FTL branch being checked out: pi-hole/FTL#1688

Related issue or feature (if applicable): N/A

Pull request in docs with documentation (if applicable): N/A

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[yubiuser]

I don't think we should show the "total-ever seen clients". What is the use of knowing 612 clients have ever been on my network? With devices using random MAC, IPv6 prefix change and guests coming and going this number will only increase.

We also don't show the number of ever handled queries or ever blocked queries.

[rdwebdesign]

I think I agree with yubiuser.

Dashboard only shows data (total queries, blocked queries, percentage, graphics, top lists) from the last 24 hours.

[DL6ER]

Total clients, however, constantly eat up resources as we need to allocate DNS cache per-client as some clients may block a domains and others not (due to groups). This is not an issue for queries, upstreams, etc. which can come and go any not cause memory accumulation over time. If you see one million total clients, it may be a good idea to restart FTL.

If you still think this should be removed, I'll do this.

[yubiuser]

Total clients, however, constantly eat up resources
If you see one million total clients, it may be a good idea to restart FTL.

I'm not sure, if users are aware of those facts.
The better solution to this would probably be a warning in the message system. (E.g. "Fom 1000 clients 900 haven't been seen in 90 days. Those still consume resources. Consider restarting FTL")

If you still think this should be removed, I'll do this.

I still think so, but we can have a night in-between before making a decision.

[DL6ER]

Possible compromise pushed (hover text):