Fix the graphics time range when MAXLOGAGE is different than 24h

[rdwebdesign]

What does this PR aim to accomplish?:

Fix #2584

Screenshot showing the issue:

How does this PR accomplish the above?:

The PHP code now take into account the current time and the value from MAXLOGAGE option to limit the values received from the API.
Now, it only accepts values on the expected time range and ignores data outside the range.
This prevents empty timeslots from showing on the graphics.

Link documentation PRs if any are needed to support this PR:

none

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[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/option-for-change-time-range-on-the-dashboard/62634/10