net/http: update bundled x/net/http2 and delete obsolete http2inTests
http2inTests is no longer needed after go.dev/cl/708135 and should be
deleted. To prevent errors in future vendored dependency updates,
h2_bundle.go is also updated together in this change.
Change-Id: I7b8c3f6854203fab4ec639a2a268df0cd2b1dee7
Reviewed-on: https://go-review.googlesource.com/c/go/+/708595 Reviewed-by: Damien Neil <dneil@google.com> Reviewed-by: Nicholas Husin <husin@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>