Remove dead code

The runnable is never used, which should be removed with
I3210df9bcc087f5fba712e0e7ac4922475c3b88d

Bug: 163976519
Flag: EXEMPT remove dead code
Test: CtsWindowManagerDeviceInsets
Change-Id: Ic30bef4bcd22bbb35625fa4da320b99eab650db0
1 file changed