Unbreak this extension by killing $wgCategoryTreeDynamicTag

Somewhere along the line this extension's JS was refactored,
except for a part which was left as is, and was calling functions
since renamed, and still assuming top loaded...

Just kill $wgCategoryTreeDynamicTag, since it doesn't work, it
hasn't worked for a while, and it looks like a bit of work to
make it work properly. Also change the cache disabling defaults
of this extension to be 6 hours so it doesn't cause explosions.

If someone wants the feature represented by $wgCategoryTreeDynamicTag
they can of course re-introduce it in a subsequent commit. In the
mean time, let's not have broken code.

Bug: 59798
Change-Id: I01e0bd264e2a007cd9de017d10667bb2809d70a9