fix test cases

Author: leniatgh

tests/2017-12-01/Microsoft.DBforMySQL.tests.json

@@ -279,7 +279,7 @@
       "definition":"https://schema.management.azure.com/schemas/2017-12-01/Microsoft.DBforMySQL.json#/resourceDefinitions/servers_securityAlertPolicies",
       "json":{
         "apiVersion":"2017-12-01",
-        "name":"myServer/Default",
+        "name":"myServer/default",
         "type":"Microsoft.DBforMySQL/servers/securityAlertPolicies",
         "properties":{
           "state":"Enabled"

tests/2017-12-01/Microsoft.DBforPostgreSQL.tests.json

@@ -279,7 +279,7 @@
       "definition":"https://schema.management.azure.com/schemas/2017-12-01/Microsoft.DBforPostgreSQL.json#/resourceDefinitions/servers_securityAlertPolicies",
       "json":{
         "apiVersion":"2017-12-01",
-        "name":"myServer/Default",
+        "name":"myServer/default",
         "type":"Microsoft.DBforPostgreSQL/servers/securityAlertPolicies",
         "properties":{
           "state":"Enabled"

tests/2018-06-01/Microsoft.DBforMariaDB.tests.json

@@ -279,7 +279,7 @@
       "definition":"https://schema.management.azure.com/schemas/2018-06-01/Microsoft.DBforMariaDB.json#/resourceDefinitions/servers_securityAlertPolicies",
       "json":{
         "apiVersion":"2018-06-01",
-        "name":"myServer/Default",
+        "name":"myServer/default",
         "type":"Microsoft.DBforMariaDB/servers/securityAlertPolicies",
         "properties":{
           "state":"Enabled"