nsqadmin: fix counter view

[dudleycarr]

Fixes #747

Two bugs are addressed on the counter view:

1. The increment counter animation is unbounded, causing the counter to exceed the true message processing count. The counter jumps back to the true message processing count after the API poll request.
2. The message processed graph below the counter doesn't properly handle the timeframe selector. The graph briefly updates when selecting the new timeframe but reverts to the timeframe at page load after the next API poll request.

Video below shows the first bug in the nsqadmin running on 4171. The nsqadmin on 4181 has the PR fix.

Screen.Recording.2023-10-25.at.6.18.32.AM.mov

[jehiah]

I haven't looked at this page recently... it's always a blast to see. Below from one of my clusters.