* Tests: Replace YAML tests with ESTestRestCase to be able to wait for events
The YAML tests did not have any possibility to wait for the watches to
be created. A hard ten second timeout was used, that could not be
aborted, by simulating a sleep when waiting for a number of nodes that
never occured in the cluster.
This commit replaces those waiting YAML tests with ESRestTestCases, that
use `assertBusy()` to exit early once the watches have been added. Also
this increases the wait time if needed, as these tests tend to fail on
CI.
relates elastic/x-pack-elasticsearch#3217
Original commit: elastic/x-pack-elasticsearch@74b9945d88
eaf67f8bc2