[netstack] Improve eBPF matchers testing in netstack filter tests.

Refactored filter tests to separate matcher state from matcher
definition. This ensures that matcher state is never shared between
matchers installed for different hooks. This allows to configure each
eBPF matcher instance to match only on some port numbers. This
is expected to resolver the flake observed in these tests in the past.

Bug: 455585276
Fixed: 470988815
Change-Id: I29c4b21e9e78db9d6991a15911daaab8527c9846
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1462728
Reviewed-by: Bruno Dal Bo <brunodalbo@google.com>
Commit-Queue: Sergey Ulanov <sergeyu@google.com>
12 files changed