Minimize the time spent in the locks timeout test by using tighter timings.

* subversion/tests/libsvn_fs/locks-test.c
  (lock_expiration): expire after 2 secs; wait for 3

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1544727 13f79535-47bb-0310-9956-ffa450edef68