In order to check for the REST tests if triggering of watches with
security enabled works as expected, we have to add a watch and wait for
its background execution. In the REST tests the only wait is to wait for
this with a timeout. If the timeout is reached but the watch has not
been executed yet, the test will fail.
This commit replaces the YAML with a java based REST test, so that
helper methods like assertBusy() can be used and waiting for a watch to
be executed now works as expected.
relates elastic/x-pack-elasticsearch#3753
Original commit: elastic/x-pack-elasticsearch@fc39636ef7
90c360d9d0