ctdb-tests: Drop uses of "onnode any ..." in testcases

ctdb-tests: Drop uses of "onnode any ..." in testcases

It would be nice to get rid of "onnode any".  There's no use making
tests nondeterministic.  If covering different cases matters then they
should be explicitly handled.

In most places "any" is replaced by "$test_node".  In some cases,
where $test_node is not set, a fixed node that is already used
elsewhere can be reused.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>