Change Dashboard query activity graph labels to reduce confusion

From here: https://www.reddit.com/r/pihole/comments/f3jsoo/what_on_earth_happened_almost_450_clients_there/

The graph labels confused me in the beginning too. Maybe the titles could be tweaked for v5?

Queries over last 24 hours

Clients (over time)

to

Queries Forwarded and Blocked - over the last 24 hours

Queries by Client - over the last 24 hours

Or something similar to reduce the initial confusion?