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Description of problem:
As part of the fix for [1], users can now add `:async_ssh: true` in /etc/smart_proxy_dynflow_core/settings.d/remote_execution_ssh.yml to make all remote execution jobs run asynchronously.
Users shouldn't have to manually enter this option and restart satellite to use it. At the least, an option should be added to the installer to enable/disable this feature.

https://bugzilla.redhat.com/show_bug.cgi?id=1386270

Version-Release number of selected component (if applicable):
6.3 Snap 35

How reproducible:
N/A

Steps to Reproduce:
1. Check to see if the option was added to the installer
2. Verify that the change was made to the config file listed above.
3. (Optional) follow the verification steps in https://bugzilla.redhat.com/show_bug.cgi?id=1386270#c16

Actual results:
N/A