Stabilize flaky tests by adding packet delay

Introduce a 3-second delay in each packet send.
Before sending each packet, wait for 3 seconds to give the
firmware time to turn on the APF.
The firmware may have throughput calculation logic that
depends on a certain time window.

Flag: EXEMPT test only
Bug: 434614102
Test: atest CtsConnectivityMultiDevicesTestCases:ApfV6Test
Test: ./cts-tradefed run commandAndExit cts \
      -m CtsConnectivityMultiDevicesTestCases \
      -t ApfV6Test --shard-count 2
Change-Id: I0807562cd87cbfe90c90d48cf2d0e41673c153b0
1 file changed