… installed (elastic#157869)

## Summary

Fixes elastic#157345

When a package with a changed `index.mode` or `source.mode` setting is
installed, Fleet will now automatically perform a rollover to ensure the
correct setting is present on the resulting backing index.

There is an issue with Elasticsearch wherein toggling these settings
back and forth will incur a backing index range overlap error. See
elastic/elasticsearch#96163.

To test
1. Install the `system` integration at version `1.28.0`
2. Create an integration policy for the `system` integration (a standard
default agent policy will do)
3. Enroll an agent in this policy, and allow it to ingest some data
4. Confirm that there are documents present in the
`metrics-system.cpu-default` data stream, and note its backing index via
Stack Management
5. Create a new `1.28.1` version of the `system` integration where
`elasticsearch.index_mode: time_series` is set and install it via
`elastic-package install --zip`
6. Confirm that a rollover occurs and the backing index for the
`metrics-system.cpu-default` data stream has been updated

### Checklist

Delete any items that are not applicable to this PR.

- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

---------

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>
(cherry picked from commit 22e3847)