CI: use svr_id for Ping in RFsim-based tests

This is not really used as of now, because most IPs are hardcoded. See
one of the next commits for the use of this.

To make sure that we have the correct IP, there is some code that
verifies that a hardcoded IP and the CN IP would be the same.

Note: need two separate ci_infra.yaml entries, because
- for FlexRIC, the container name is different (is the tutorial CN)
- for RFsim5G E1, we don't have ext-dn => ping UPF

ci-scripts/ci_infra.yaml

@@ -386,6 +386,15 @@ rfsim5g_ext_dn:
   NetworkScript: docker exec rfsim5g-oai-ext-dn ip a show dev eth0
   CmdPrefix: docker exec rfsim5g-oai-ext-dn
 
+oai_ext_dn:
+  Host: "%%current_host%%"
+  NetworkScript: docker exec oai-ext-dn ip a show dev eth0
+  CmdPrefix: docker exec oai-ext-dn
+
+rfsim5g_5gc_fixed_ip:
+  Host: "%%current_host%%"
+  NetworkScript: echo "inet 12.1.1.1"
+
 rfsim4g_ue:
   Host: "%%current_host%%"
   NetworkScript: docker exec rfsim4g-oai-lte-ue0 ip a show dev oaitun_ue1