QUIC MULTISTREAM TEST: Fix script 38 stochastic failure on Windows

QUIC MULTISTREAM TEST: Fix script 38 stochastic failure on Windows

The QUIC fault injector frame injection functionality injects injected
frames on whatever EL we happen to be using to generate a packet in.
This means we sometimes inject the frame into a packet type it is not
allowed to be in, causing a different error code to be generated.

Fix this by making sure the connection is fully established before
trying to generate the frame in question.

Fixes #22348.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22578)