net/http: handle new HTTP/2 error for 1xx limit exceeded
CL 615295 changed the error message produced by the HTTP/2
implementation when a server sends more 1xx headers than expected.
Update a test that checks for this error.
For #65035
Change-Id: I57e22f6a880412e3a448e58693127540806d5ddb
Reviewed-on: https://go-review.googlesource.com/c/go/+/625195 Reviewed-by: David Chase <drchase@google.com> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>