Revert "Adds -XdisableUpdateCheck to all GWT commands."

The "pings" are important to gather statistics about GWT usage, and
harmless for users (and they happen in in a separate thread so they don't
even slow things down).

This reverts commit 94b87b97d84a8cf4f161f04c74aaad421c567e5b.
Merge commit 'd546c1eca1c99573e10dc5f2ed070b19c790a18d'

Change-Id: If455fa2381aac09333be75e9258d51664dd1e007