Remove unnecessary background in call log.

Background in call log fragment is same as the activity. It's unnecessary and only reduces rending performances.
Verified by hand that it looks same as before.

GPU Overdraw:
Before: https://screenshot.googleplex.com/y1HNFiae1j7
After: https://screenshot.googleplex.com/mQFxyWEhkFm

Performance test:

Before:

Total frames rendered: 668
Janky frames: 35 (5.24%)
50th percentile: 7ms
90th percentile: 11ms
95th percentile: 16ms
99th percentile: 73ms
Number Missed Vsync: 18
Number High input latency: 1
Number Slow UI thread: 35
Number Slow bitmap uploads: 0
Number Slow issue draw commands: 2

After:

Total frames rendered: 736
Janky frames: 32 (4.35%)
50th percentile: 6ms
90th percentile: 11ms
95th percentile: 13ms
99th percentile: 61ms
Number Missed Vsync: 15
Number High input latency: 0
Number Slow UI thread: 31
Number Slow bitmap uploads: 0
Number Slow issue draw commands: 3

Test: manual
PiperOrigin-RevId: 162392495
Change-Id: I726cd06518d282abe68eb1ff16db82c9a3e6d291

0 files changed, 0 insertions, 0 deletions