Installer: Remove wgResourceLoaderMaxQueryLength in LocalSettings

Installer: Remove wgResourceLoaderMaxQueryLength in LocalSettings

This can change from one web server to another. Hardcoding it
in LocalSettings is unnececary (and could even cause problems
when a MediaWiki install is moved to a server with a lower
limit than the original server, as ResourceLoader would still
be acting on the old limit).

Similar to how wgUsePathInfo is currently dynamically set.

The less cruft in LocalSettings by default the better imho.
Except for stuff that makes sense to be sticky, explicit and
cached. Or stuff that is every commonly enabled and is therefor
convinient (such as wgEnableUploads/wgUseInstantCommons).

Change-Id: I58cb185f8dc1650a76c60c7fd04767fb74b32be2