mediawiki.log: Remove call to console.trace() for each warning

mediawiki.log: Remove call to console.trace() for each warning

When code that accesses a deprecated property is called multiple times,
every time a deprecation message is logged and a stack trace produced.

And all synchronously as well. This creates a duplicative mess in the
console.

Per T103891, T103610, and reports on IRC, this appears to have a
tendency to crash Firebug.

While less convenient, there are other ways to get the calling
function from a warning (e.g. debugger, breakpoints, pause/step
execution). We don't call it for mw.log.error, either.

This should help reduce noise, speed up execution path, and hopefully
prevent such crashes in the future.

Change-Id: I80428a5e80dbb84b93be2f10340fe29d9bef12d3