[Metricbeat] Add CouchDB Dashboard

[sorantis]

Partially addresses #10594.

This CouchDB dashboard visualizes the following metrics:

  - name: couchdb.server.httpd.view_reads
    description: Number of view reads.
  - name: couchdb.server.httpd.temporary_view_reads
    description: Number of temporary view reads.

  - name: couchdb.server.couchdb.open_databases
    description: Number of open databases.

  - name: couchdb.server.httpd_status_codes.*
    description: HTTP status code response rates (200, 201, 202, 400, 401, 403, 404, 405, 409, 500).

  - name: couchdb.server.httpd_request_methods.*
    description: HTTP request method rates (GET, POST, PUT, DELETE, HEAD, COPY).

  - name: couchdb.server.couchdb.database_reads
    description: Number of times a document was read from a database.
  - name: couchdb.server.couchdb.database_writes
    description: Number of times a database was changed.

  - name: couchdb.server.httpd.view_reads
    description: Number of view reads.
  - name: couchdb.server.httpd.temporary_view_reads
    description: Number of temporary view reads.

  - name: couchdb.server.couchdb.auth_cache_hits
    description: Number of authentication cache hits.
  - name: couchdb.server.couchdb.auth_cache_misses
    description: Number of authentication cache misses.

Dashboard snapshot:

[jsoriano]

Nice dashboard!

Are open databases the number of open connections? I think it is useful to see the number of connections over time.

[sorantis]

Are open databases the number of open connections? I think it is useful to see the number of connections over time.

Yes. Changed to a TS graph.

[jsoriano]

Added a couple of minor comments, once resolved this looks good to go.

[jsoriano]

The ECS suffix was intended for migration of dashboards from 6.x to 7.x, it is not needed on dashboards created after 7.0.

[jsoriano]

Why are you adding the newlines at the end \n\n?