Fix a silently failing cts test

WebViewHostSideMultipleProfileTest#testManagedProfile was failing to
set the profile owner silently because the shell command 'dpm
set-profile-owner' was not returning an error code, this was discovered
after a change was made to the underlying shell command mechanism and
the command started returning the failure.

Test: atest --verbose com.android.cts.webkit.WebViewHostSideMultipleProfileTest#testManagedProfile
Bug: 173381875
Change-Id: Ie1a61fd1561c52520b65fb1010cbe4384965ef78