Revert "Update jquery.ui Vector theme to 1.9.2"

This change messed up jquery.ui.button styling on Commons, so we're reverting.

This reverts commit 7bb0c9a01eb0266696a9c3989572ae3a5b67bfdd.

Change-Id: Ibef35ce9f5a642f89bf70ec891ba1425f678ec1e