Golang x/net/quic: TestStreamTransfer failures

#!watchflakes
default <- pkg == "golang.org/x/net/quic" && test == "TestStreamTransfer"

Issue created automatically to collect these failures.

Example (log):

=== RUN   TestStreamTransfer
    endpoint_test.go:50: read data mismatch (got 1048576 bytes, want 1048576
--- FAIL: TestStreamTransfer (0.05s)

— watchflakes

Comment From: gopherbot

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "golang.org/x/net/quic" && test == "TestStreamTransfer"

2025-08-07 18:37 x_net-gotip-windows-amd64 net@af6926ea go@1f7ffca1 x/net/quic.TestStreamTransfer (log)

=== RUN TestStreamTransfer endpoint_test.go:50: read data mismatch (got 1048576 bytes, want 1048576 --- FAIL: TestStreamTransfer (0.05s)

— watchflakes