Raise `ethmonitor` intervals to 15 seconds.

Also use a resource template for both `ethmonitor` resources,
so we can shorten the configuration and easily make changes
to both resource sets.
Use the location constraint suggested by `ethmonitor` documentation.

Instead of a `colocation` constraint, we now anti-locate a resource:
it cannot run if the result of the relevant "ethmonitor" check is 0.
Remove unused id on `lustre-target-template` operations.