Fix compilation errors against stable-3.6

* apache.commons.lang is no more available in the Gerrit dependencies.
Move to the more recent lang3 version.
* update Change lastUpdatedOn parameter to use Instant, accordingly to
new Change constructor signature [1].
* avoid to hardcode ALL as log level in the test utility.
Set the value coming from the logging event. Tests were failing since
they weren't matching the correct log level.

[1]: https://gerrit.googlesource.com/gerrit/+/refs/heads/stable-3.6/java/com/google/gerrit/entities/Change.java#441

Bug: Issue 15842
Change-Id: I295a4f37eea2d6df0142bb8d6024d75da956a9dd