Remove collectd/elasticsearch monitor

[atoulme]

Description:

This PR removes the collectd/elasticsearch monitor in favor of the elasticsearch monitor.

As noted in the deprecation notice of the monitor:

    Monitors ElasticSearch instances. We strongly recommend using the
    [elasticsearch](./elasticsearch.md) monitor instead, as it will
    scale much better.

[rmfitzpatrick]

please replace w/ logged deprecation notice for at least a release

warning exists