[ML] Data Frame Analytics results UI - no warning if no index pattern exists

[LucaWintergerst]

Kibana version: 7.9.2

Elasticsearch version: 7.9.2

Server OS version: Elastic Cloud

Browser version: Version 85.0.4183.121 (Official Build) (64-bit)

Browser OS version: MacOs Catalina 10.15.7 (19H2)

Original install method (e.g. download page, yum, from source, etc.): Cloud

Describe the bug:

Viewing the results of an outlier detection job shows an empty view and no error if no index pattern with the same name as the results index is present. The chrome dev console also does not log an error or a warning. @walterra mentioned that there should be a popup telling the user to create the index pattern (or at least telling the user that the pattern is missing)

Steps to reproduce:

1. create outlier job without index pattern
2. view results of the job

Expected behavior:

Screenshots (if relevant):

Errors in browser console (if relevant):

Provide logs and/or server output (if relevant):

Any additional context:

[elasticmachine]

Pinging @elastic/ml-ui (:ml)

[peteharverson]

On latest master (7.10.0), this behavior still occurs if an index pattern exists for neither the job results index or the source index.

If just the index pattern for the results index is missing, you do see a warning:

[walterra]

@luca This should now be fixed for 7.10+ via #81123