coder: remove some unnecessary SSH settings (#353)

- Removed ServerAliveInterval and ServerAliveCountMax from config-ssh
  settings. These settings are opinionated about when idle sessions
  should disconnect and should be inherited from the user's global settings.
  'coder config-ssh' should only write configuration options that are
  necessary for 'coder sh' and its variants to succeed.

Author: sreya

internal/cmd/configssh.go

@@ -230,8 +230,6 @@ func makeSSHConfig(host, userName, workspaceName, privateKeyFilepath string, tun
    ConnectTimeout=0
    IdentitiesOnly yes
    IdentityFile="%s"
-   ServerAliveInterval 60
-   ServerAliveCountMax 3
 `, workspaceName, workspaceName, workspaceName, privateKeyFilepath)
 	}
 
@@ -243,8 +241,6 @@ func makeSSHConfig(host, userName, workspaceName, privateKeyFilepath string, tun
    ConnectTimeout=0
    IdentitiesOnly yes
    IdentityFile="%s"
-   ServerAliveInterval 60
-   ServerAliveCountMax 3
 `, workspaceName, host, userName, workspaceName, privateKeyFilepath)
 }