Update tugboat host to use version 20 of Docker

[acrollet]

Description

Follow up from #6216.

Acceptance Criteria

• Testable_Outcome_X
• Testable_Outcome_Y
• Testable_Outcome_Z
• Requires design review

[ndouglas]

Confirmed this morning that this is still a thing:

sh-4.2$ docker version
Client:
 Version:           19.03.13-ce
 API version:       1.40
 Go version:        go1.13.15
 Git commit:        4484c46
 Built:             Mon Nov  2 19:22:46 2020
 OS/Arch:           linux/amd64
 Experimental:      false
Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get http://%2Fvar%2Frun%2Fdocker.sock/v1.40/version: dial unix /var/run/docker.sock: connect: permission denied

[cweagans]

Closing in favor of #7667 since there is some other discussion/info there.