[3281] Fixed comments in the unit tests checking subnet ids.

src/bin/dhcp4/tests/config_parser_unittest.cc

@@ -611,8 +611,7 @@ TEST_F(Dhcp4ParserTest, multipleSubnets) {
 // This test checks that it is possible to assign arbitrary ids for subnets.
 TEST_F(Dhcp4ParserTest, multipleSubnetsExplicitIDs) {
     ConstElementPtr x;
-    // Collection of four subnets for which subnet ids should be
-    // autogenerated - ids are unspecified or set to 0.
+    // Four subnets with arbitrary subnet ids.
     string config = "{ \"interfaces\": [ \"*\" ],"
         "\"rebind-timer\": 2000, "
         "\"renew-timer\": 1000, "
@@ -673,8 +672,7 @@ TEST_F(Dhcp4ParserTest, multipleSubnetsExplicitIDs) {
 // Check that the configuration with two subnets having the same id is rejected.
 TEST_F(Dhcp4ParserTest, multipleSubnetsOverlapingIDs) {
     ConstElementPtr x;
-    // Collection of four subnets for which subnet ids should be
-    // autogenerated - ids are unspecified or set to 0.
+    // Four subnets, two of them having the same id.
     string config = "{ \"interfaces\": [ \"*\" ],"
         "\"rebind-timer\": 2000, "
         "\"renew-timer\": 1000, "

src/bin/dhcp6/tests/config_parser_unittest.cc

@@ -626,8 +626,7 @@ TEST_F(Dhcp6ParserTest, multipleSubnets) {
 // This checks that it is possible to assign arbitrary ids for subnets.
 TEST_F(Dhcp6ParserTest, multipleSubnetsExplicitIDs) {
     ConstElementPtr x;
-    // Collection of four subnets for which ids should be autogenerated
-    // - ids are unspecified or set to 0.
+    // Four subnets with arbitrary subnet ids.
     string config = "{ \"interfaces\": [ \"*\" ],"
         "\"preferred-lifetime\": 3000,"
         "\"rebind-timer\": 2000, "