Ensure future are reset before being set

This avoid async flakiness when test assert the future is null before
enqueue next packet

Test: atest --host
Bug: 264572812
Bug: 265213364
Merged-In: Iac9e2f0722db5d6d4c148358d96bb1df1f00aebf
(cherry picked from commit 0c7e0b3e)
Change-Id: I3209a9d2fa4a0fcec400a99b58ad7d741f522b85