This commit adds a new flag to shuffle all the test cases before running
them so tests which require lots of blocks to be mined are less likely
to be run in the same tranch.
The other benefit is this approach provides a more efficient way to
figure which tests are broken since all the differnet backends are
running different tranches in their builds, we can identify more failed
tests in one push.
For some reason lnd doesn't properly shut down on some windows itests,
and the process still running makes it impossible to access its log
files.
So for the Windows integration test, we attempt to kill the whole
process tree once the process indicates it is done.
When one of the itest tranches fails, because we are running tests in
parallel, other tranches will still be running, which caused 7z to fail
at zipping the logs because race reads. This commit fixes it by making
sure we are waiting other tranches to finish before moving to zipping
and uploading the logs.
