Attempt to fix the CI finalization test

Since I'm not able to reproduce the finalization failure locally
and it does happen only sporadically, one possible explanation is
that the introduction of keystores lead to a slower initialization
of the beacon nodes which somehow interferes with their behavior
during the initial slots.

If increasing the start-up delay fixes the problems, the hypothesis
will be confirmed.

scripts/launch_local_testnet.sh

@@ -153,7 +153,7 @@ BOOTSTRAP_IP="127.0.0.1"
 	--output-bootstrap-file="${NETWORK_DIR}/bootstrap_nodes.txt" \
 	--bootstrap-address=${BOOTSTRAP_IP} \
 	--bootstrap-port=${BASE_PORT} \
-	--genesis-offset=30 # Delay in seconds
+	--genesis-offset=60 # Delay in seconds
 
 ./scripts/make_prometheus_config.sh \
 	--nodes ${NUM_NODES} \