Fix brightness type bug

When brightness adjusts to 1.0 or 0.0, the double will become integer.
(1 and 0) Now put string brightness value in the json file and handle it
when convert to bundle from Json.

Bug: 421266416
Flag: EXEMPT bugfix
Test: tested on gambit and checked database
Change-Id: I346854aa1f77c89fe3e5d6fb8095aa0d9f9fe7d4