[netstack3] Change TCP port allocation algorithm

Use RFC 6056 Algorithm 1 instead of Algorithm 3/4 since we may have
security problems if our bucket sizes aren't big enough.

Bug: 42182649

Change-Id: I06339ea8db243dbd9232dfc42ecbdf4089597529
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/999635
Commit-Queue: Auto-Submit <auto-submit@fuchsia-infra.iam.gserviceaccount.com>
Reviewed-by: Bruno Dal Bo <brunodalbo@google.com>
Fuchsia-Auto-Submit: Zeling Feng <zeling@google.com>