Summary:
Allow manual configuration of 'AutoStartSSHAgent' when SSH Client Type is set to OpenSSH

Description:
I would like to request a fix to allow users to manually toggle the "AutoStartSSHAgent" setting when using OpenSSH.

Current Situation:
I am using "System Git" and "External OpenSSH" in my environment. In this setup, ssh-agent is already running and managed externally. However, in Sourcetree, when I select "OpenSSH" as the SSH Client Type, the "AutoStartSSHAgent" option is forced to "True" and becomes grayed out (unclickable).

The Problem:
Because this setting is forced to True, Sourcetree attempts to start its own ssh-agent every time the application starts or the Options window is closed. This causes a conflict with my existing, running ssh-agent, resulting in error messages.
Furthermore, even if I manually set 'AutoStartSSHAgent' to 'False' in the configuration file, the setting is automatically reverted to 'True' simply by opening the Options dialog in Sourcetree. This makes it impossible to maintain the desired configuration.

Requested Change:
Please make the "AutoStartSSHAgent" setting configurable (True/False) even when OpenSSH is selected, so that users who already have an SSH agent running can prevent Sourcetree from attempting to start another one.