Stop resetting default browser for browser installation/clearing data/reset app preferences.

Bug: 183412485
Test: manual
Test: Install 2 3p browsers, the default browser remained untouched.
Test: Uninstall the 2 3p browsers, the default browser still remained
      untouched.
Change-Id: Ifb34505561b5e2501b3f02586b11b6d70af86d62