Remove uncompressed prebuilt dumps before building new ones

- Remove both .lsdump and .lsdump.gz files before
  create_reference_dumps.py builds new ABI dumps.
- Replace rm commands with Python built-in functions.

Bug: 120858317
Test: ./create_reference_dumps.py --llndk -libs libbinder_ndk
Change-Id: I11c50eaaba1cdd68f1f5f715293584a6fe0746c6
1 file changed