[DOCS] Update references to apps and pages: solution views and classic nav updates in Kibana #116166
Description
Follow-up to https://github.com/elastic/platform-docs-team/issues/486
With the stateful navigation updates, we need to check that the way we refer to apps and pages in our UI-related guides remains true independently of which navigation users got by default (classic or solution view).
The wording that was discussed and agreed is documented in our style guide.
This specific issue is for the 'Connectors' section in the Elasticsearch guide, especially the Connectors UI in Kibana page.
The new navigation will arrive with 8.16, so ideally updates should be done by then.
Note: There's a related issue to update the general information about search and navigation principles in Kibana https://github.com/elastic/platform-docs-team/issues/530