Increase UDP record packing time in ssl-opt.sh

The UDP tests involving the merging of multiple records into single
datagrams accumulate records for 10ms, which can be less than the
total flight preparation time if e.g. the tests are being run with
valgrind.

This commit increases the packing time for the relevant tests
from 10ms to 50ms.
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 8f64e54..a1155e8 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -2575,7 +2575,7 @@
 # server MUST NOT idle on the underlying transport after handshake completion,
 # because the ApplicationData request has already been queued internally.
 run_test    "Event-driven I/O, DTLS: session-id resume, UDP packing" \
-            -p "$P_PXY pack=10" \
+            -p "$P_PXY pack=50" \
             "$P_SRV dtls=1 event=1 tickets=0 auth_mode=required" \
             "$P_CLI dtls=1 event=1 tickets=0 reconnect=1" \
             0 \
@@ -3832,7 +3832,7 @@
             -c "HTTP/1.0 200 OK"
 
 run_test    "DTLS proxy: multiple records in same datagram" \
-            -p "$P_PXY pack=10" \
+            -p "$P_PXY pack=50" \
             "$P_SRV dtls=1 debug_level=2" \
             "$P_CLI dtls=1 debug_level=2" \
             0 \
@@ -3840,7 +3840,7 @@
             -s "next record in same datagram"
 
 run_test    "DTLS proxy: multiple records in same datagram, duplicate every packet" \
-            -p "$P_PXY pack=10 duplicate=1" \
+            -p "$P_PXY pack=50 duplicate=1" \
             "$P_SRV dtls=1 debug_level=2" \
             "$P_CLI dtls=1 debug_level=2" \
             0 \