[Geo Alerting] - Kibana does not recognize a valid geo_shape index when attempting to create a Tracking Containment alert.

[Jaraxal]

Kibana version: 7.12

Elasticsearch version: 7.12

Server OS version: N/A

Browser version: Chrome Version 89.0.4389.90 (Official Build) (x86_64)

Browser OS version: Mac OS 11.2.3

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

Describe the bug:

Kibana is not recognizing a valid index for defining the boundary used in a tracking containment geo alert. Kibana says no valid indexes found. I have an index pattern created and a properly indexed geo_shape document in the index. I was able to successfully use this index to plot the geo_shape on Kibana Maps.

Steps to reproduce:

1. Define a boundary index:

`
PUT /geo-boundary
{
"mappings": {
"properties": {
"location": {
"type": "geo_shape"
}
}
}
}

GET /geo-boundary/_search

POST /geo-boundary/_doc
{
"location" : {
"type" : "polygon",
"coordinates" : [
[
[
-77.18985,
38.89482
],
[
-77.18985,
38.86802
],
[
-77.10519,
38.86802
],
[
-77.10519,
38.89482
],
[
-77.18985,
38.89482
]
]
]
}
}
`
2. Create a Kibana index pattern for the index.
3. Attempt to create a tracking containment alert.
4. Kibana says it can't find a valid index.

Expected behavior:
Kibana should find and be able to use the index created above.

Screenshots (if relevant):
Kibana Index Pattern:

Tracking Containment Alert Error:

Errors in browser console (if relevant):

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

Any additional context:
cc: @aaronjcaldwell

[kmartastic]

I could not repro in default cloud instance.

[elasticmachine]

Pinging @elastic/kibana-gis (Team:Geo)

[nreese]

Steps to reproduce:

1. On a fresh install, create at least 10 index patterns without any geo fields.
2. create an index pattern with geo_shape field.
3. geo index pattern select in either alert configuration or maps add layer will be disabled with message that there are no index patterns with geo fields.

The issue has always existed. Prior to 7.12, the first 100 index patterns where searched for index patterns with geo fields. #92093, merged in 7.12, made this issue much more severe. The PR attempted to up the number of index patterns to 1000 but instead resulted in just 10 index patterns to be searched while looking for index patterns with geo fields.

Working on a fix for 7.12.1