When a painless exception is raised in the script condition, it was not bubbled up due to
catching exceptions on during execution. This removes the different catching of exceptions
and allows the watch record construct to contain an exception that is also serialized correctly
so that it can be stored in the watch history but also returned in the execute watch API.
This also updates the watch history template, so that exceptions are not indexed, but logged.
Relates elastic/elasticsearch#2587
Original commit: elastic/x-pack-elasticsearch@4dffb672bf
e8c1e7f9d8