Update dumpsys user parser for user serial number.

Now the output line has isPrimary and looks like this:
UserInfo{0:Owner:13} serialNo=0 isPrimary=true

Bug: 135594398
Test: atest CrossProfileAppsHostSideTest#testPrimaryUserToPrimaryUser
Change-Id: I2091d49fabae1e2109efabed07583a8639886871