[net_test_utils] correct the return path of stop_tcpdump

Fix a issue that the return path of stop_tcpdump was
changed to directory accidentally

Bug: 171472638
Test: Local
Change-Id: Idcd2e2de16a9e465a2c40c99daf9814aaefac9d7
1 file changed
tree: 14c01613118ce1c821ef20de111652580281f8a1
  1. acts/
  2. tools/
  3. wts-acts/
  4. Android.mk
  5. OWNERS
  6. PREUPLOAD.cfg