Performance of mediawiki.searchSuggest.js

Two tiny performance improvements.

The complexity of a regular expression is not needed to check if a
string contains a character. string.match() returns an array of
matches which is not used anyway in this case. Either
string.indexOf() or RegExp.test() should be used.

Duplicate jQuery call merged.

Change-Id: Ifec79eada70181df0d56c583ef832ee82594620e