Cleanup Bluetooth build files

This commit cleans up:
- find command does not support bracket {} in a genrule command, resulting
build noise. Use a for loop to mitigate the message.
- LOCAL_host_python_libraries is a remaining variable and not defined at all.

Bug: 338000376
Test: m bluetooth_stack_with_facade
Change-Id: Iee665089281d93d02ea0b67e2f2acdae438e2ecf