Draft: GDK integration branch for "Remote Development Integration Branches"

What does this merge request do and why?

This is the main MR/branch in the gitlab-development-kit project to reflect the architectural spike Category:Remote Development work.

See details in:

• The integration branch docs: https://gitlab.com/gitlab-org/remote-development/gitlab-remote-development-docs/-/blob/main/doc/integration-branch-process.md
• The associated parent issue: Tracking Issue for Remote Development Integrati... (gitlab#383997 - closed)

Included changes

Changes to GDK config to support Remote Development GA4K module.

Poll period configuration

1. Allows you to override the agent.gitlab_k8s_agent.remote_dev_poll_period in gitlab-k8s-agent-config.yml via gdk.yml, without it being deleted by gdk reconfigure. Adds gitlab_k8s_agent.remote_dev_poll_period config entry (default 1s), controllable via the following gdk.yml setting.

gdk.yml:

gitlab_k8s_agent:
  remote_dev_poll_period: 2s

Impacted categories

The following categories relate to this merge request:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

Merge request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise an issue to follow-up.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.