ZookeeperLockChecker.invalidateCache isn't very precise

[ctubbsii]

The invalidateCache method in ZooKeeperLockChecker was changed in #5008 to match on a startsWith path rather than an exact match. It works, but may invalidate more than needed, because it matches on things more broadly. It could be modified to add the slash delimiters on the .startsWith() parameter and around the .contains() parameter so that it invalidates more narrowly. However, this probably isn't a significant improvement, and may not actually matter.