JavaScriptMinifier: Remove support for unused $maxLineLength param

JavaScriptMinifier: Remove support for unused $maxLineLength param

Follows-up 93b8023946b0e.

The $wgResourceLoaderMinifierMaxLineLength config var was deprecated
in MediaWiki 1.27. The parameter of minify() was not used by other
code, and no new usage has been introduced since then, either.

Remove the feature from JavaScriptMinifier, and add a release note.
The 1.31 release notes already contain a note about the removal
of the configuration variables.

The feature was not covered by unit tests.

Change-Id: I38eb4187e3a8e2d882f317481b43f0bf6ac3bada