Give DTLS tests more time to complete

Increase the timeout for DTLS tests to 10 seconds.
But do that only for DTLS as this would waste time
for other tests, most of the TLS tests do not need
this at all.

Fixes #26491

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/26502)

(cherry picked from commit b999ea6bc4)

util/perl/TLSProxy/Proxy.pm

@@ -293,7 +293,7 @@ sub start
     open(my $savedin, "<&STDIN");
 
     # Temporarily replace STDIN so that sink process can inherit it...
-    open(STDIN, "$^X -e 'sleep(1)' |");
+    open(STDIN, "$^X -e 'sleep(10)' |") if $self->{isdtls};
     $pid = open(STDIN, "$execcmd 2>&1 |") or die "Failed to $execcmd: $!\n";
     $self->{real_serverpid} = $pid;