Redirects for drilldown links

[KOTungseth]

Summary

loses #83268

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: aa9e4b5

Metrics [docs]

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
core	657.9KB	657.9KB	-18.0B

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

[Dosant]

This fix would work for 7.10.x branch and for future 7.10.1 release,
but 7.10.0 was released with docsLinks prior #82081

Which are:

https://www.elastic.co/guide/en/kibana/7.10/url-drilldown.html#trigger-picker
https://www.elastic.co/guide/en/kibana/7.10/url-drilldown.html#templating
https://www.elastic.co/guide/en/kibana/7.10/url-drilldown.html#variables

In addition to change in this pr, I think we also need to make ^^ older links valid (at least point to something). I am not sure what is an approach we usually take in our docs in such cases

[Dosant]

I am looking at build:
https://kibana_83325.docs-preview.app.elstc.co/

As I understand we need

https://kibana_83325.docs-preview.app.elstc.co/guide/en/kibana/7.10/url-drilldown.html#trigger-picker
https://kibana_83325.docs-preview.app.elstc.co/guide/en/kibana/7.10/url-drilldown.html#templating
https://kibana_83325.docs-preview.app.elstc.co/guide/en/kibana/7.10/url-drilldown.html#variables

to open a redirect page, but they don't :(

Instead now

https://kibana_83325.docs-preview.app.elstc.co/guide/en/kibana/7.10/trigger-picker.html
https://kibana_83325.docs-preview.app.elstc.co/guide/en/kibana/7.10/templating.html
https://kibana_83325.docs-preview.app.elstc.co/guide/en/kibana/7.10/variables.html

are working, but it is not exactly what we need

I think we should create a <url-drilldown> entry in redirects with 3 subsections inside

[Dosant]

@elasticmachine merge upstream

[Dosant]

LGTM, except one link (comment below).

Also this points directly to 7.10?
Then, I assume after this merged we should make them same pr to master and also backport to 7.x.

I wonder if we should instead merge this into master and backport to 7.x and 7.10 following usual backport process?

[Dosant]

This link leads to itself. I think it should lead to url-drilldowns?

(https://kibana_83325.docs-preview.app.elstc.co/guide/en/kibana/current/drilldowns.html#url-drilldowns)

[KOTungseth]

Closed in favor of #83846.