Assert is_l2() on sub-ints cannot have address or LCP

unittest/yaml/error-bridgedomain2.yaml

@@ -4,7 +4,8 @@ test:
     expected:
      - "bridgedomain .* member .* has an LCP"
      - "interface .* is in L2 mode but has LCP name .*"
-    count: 5
+     - "sub-interface .* is in L2 mode but has LCP name .*"
+    count: 6
 ---
 interfaces:
   GigabitEthernet1/0/0:

unittest/yaml/error-bridgedomain3.yaml

@@ -6,7 +6,8 @@ test:
      - "sub-interface .* has an address but .* does not have LCP"
      - "bridgedomain .* member .* has an address"
      - "interface .* is in L2 mode but has an address"
-    count: 8
+     - "sub-interface .* is in L2 mode but has an address"
+    count: 9
 ---
 interfaces:
   GigabitEthernet1/0/0:

unittest/yaml/error-l2xc6.yaml

@@ -4,7 +4,9 @@ test:
     expected:
      - "sub-interface .* l2xc target .* cannot have an address"
      - "sub-interface .* l2xc target .* cannot have an LCP"
-    count: 2
+     - "sub-interface .* is in L2 mode but has an address"
+     - "sub-interface .* is in L2 mode but has LCP name .*"
+    count: 4
 ---
 interfaces:
   GigabitEthernet1/0/0: