[aws_logs] The Path Forward: maintain 1.x branch for pre-9.6 stacks

## Context

The `aws_logs` 2.0.0 release ([#20823](https://github.com/elastic/integrations/pull/20823)) adds Identity Federation (Cloud Connectors) support via `var_groups`. This raises the minimum required Kibana and Elastic Agent versions to `^9.6.0`. Customers on 9.4.x–9.5.x stacks cannot upgrade to 2.x.

Following the pattern established in [elastic/ingest-dev#8788](https://github.com/elastic/ingest-dev/issues/8788), a maintained 1.x branch is needed so that bug fixes and security patches can be backported to users who cannot yet upgrade to 9.6.

## Ask

@elastic/obs-ds-hosted-services — please create and maintain a `backport-1.x` (or equivalent) branch for `packages/aws_logs`, branched from the last 1.x tag, so future patches can be backported to the pre-9.6 audience.

## Related
- elastic/integrations#20823 (aws_logs 2.0.0 Identity Federation PR)

Start by inspecting packages/aws_logs and the last 1.x tag, then read the related aws_logs 2.0.0 change in #20823 and the branching pattern from ingest-dev#8788. Done means a backport-1.x or equivalent branch exists from the last 1.x tag and the maintenance path for future bug and security backports is established.

Written by the indexing model from the issue text.