Change ingress_controller fields mapping from text to keyword

[sejbot]

Describe the enhancement:

With PR #16197 filebeat now supports ingress controller logs which is great.

I would like to change the mapping of the text fields to keyword instead. These three fields would be affected:

• nginx.ingress_controller.http.request.id
• nginx.ingress_controller.upstream.alternative_name
• nginx.ingress_controller.upstream.name

Describe a specific use case for the enhancement or feature:
We have started to use the pipeline and mapping in our elasticsearch environment and would like to visualize metrics split by nginx.ingress_controller.upstream.name, which is not possible when it is a text field.

Changing mapping to keyword would solve this. And I think that the use case of visualizing the nginx.ingress_controller.upstream.name would be more common than free-text searching on the field.

[elasticmachine]

Pinging @elastic/integrations-services (Team:Services)

[elasticmachine]

Pinging @elastic/integrations-platforms (Team:Platforms)

[SHolzhauer]

Willing to pick this up, to complete this issue the type defnition in filebeat/module/nginx/* fields.yml needs to be changed right? or is there more to it?