roachtest: panic injector fails with unexpected error #148586
Description
Describe the problem
I've seen at least one case where a roachtest failed becasue of
2025-06-20T08:35:22.6507016Z (mixedversion.go:856).Run: mixed-version test failure while running step 16 (panicking system interface on node 4): unexpected error when executing panic statement on :4: dial tcp 127.0.0.1:29102: connect: connection reset by peer
The panic injector does expect to get a TCP error, but it is only looking for connection refused, not connection resets. We may need to be more permissive here.
Jira issue: CRDB-51686