Remove dividers of TopIntroPreference

- Following UX request to remove dividers of TopIntro.

Bug: 182854896
Change-Id: I601e87e8f20e25fde3197674f9503ab9dff292a0
Merged-In: I601e87e8f20e25fde3197674f9503ab9dff292a0
Test: manual
(cherry picked from commit b7f3cde58794c016df3b4d5d717d2c063c90600a)
1 file changed