Disable `NetworkControllerImpl`'s demo mode based on flag

Turns off handling of `-e mobile ...` commands from
`DemoModeController` if the new status bar mobile icon pipeline is
enabled.

This will be a requirement to transfer demo mode to the new pipeline

Bug: 249790009
Test: manual; enable demo mode and flag `606`, and send mobile demo
commands

Change-Id: I6beaccc56d2c2b816c2983c3822f0e15b022efe5