Default-disable Gitaly Praefect

Overview

With the efforts of using Raft, the Gitaly will eventually use that to replace Praefect. This means we can choose to disable Praefect by default. Most users don't benefit from using Praefect and not enabling it will simplify their setup and performance of it.

Impacted categories

The following categories relate to this issue:

• 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.

Proposal (optional)

Modify praefect.enabled to false.

Environment (optional)

• Operating system name: <!-- output of `uname -a` command -->
• Architecture: <!-- output of `arch` command -->
• The contents of your gdk.yml (if any)
• Ruby version: <!-- output of `ruby --version` command -->
• GDK version: <!-- output of `git rev-parse --short HEAD` command -->