remove the unused parameters (Azure#17236)

Author: ArcturusZhang

specification/mysql/resource-manager/Microsoft.DBforMySQL/preview/2017-12-01-preview/mysql.json

@@ -3167,17 +3167,6 @@
       "type": "string",
       "description": "The name of the location.",
       "x-ms-parameter-location": "method"
-    },
-    "SecurityAlertPolicyNameParameter": {
-      "name": "securityAlertPolicyName",
-      "in": "path",
-      "description": "The name of the security alert policy.",
-      "required": true,
-      "type": "string",
-      "enum": [
-        "default"
-      ],
-      "x-ms-parameter-location": "method"
     }
   }
 }

specification/mysql/resource-manager/Microsoft.DBforMySQL/preview/2018-06-01-privatepreview/mysql.json

@@ -3737,17 +3737,6 @@
       "description": "The name of the location.",
       "x-ms-parameter-location": "method"
     },
-    "SecurityAlertPolicyNameParameter": {
-      "name": "securityAlertPolicyName",
-      "in": "path",
-      "description": "The name of the security alert policy.",
-      "required": true,
-      "type": "string",
-      "enum": [
-        "default"
-      ],
-      "x-ms-parameter-location": "method"
-    },
     "QueryIdParameter": {
       "name": "queryId",
       "in": "path",

specification/mysql/resource-manager/Microsoft.DBforMySQL/stable/2017-12-01/ServerSecurityAlertPolicies.json

@@ -276,17 +276,6 @@
       "type": "string",
       "description": "The name of the server.",
       "x-ms-parameter-location": "method"
-    },
-    "SecurityAlertPolicyNameParameter": {
-      "name": "securityAlertPolicyName",
-      "in": "path",
-      "description": "The name of the security alert policy.",
-      "required": true,
-      "type": "string",
-      "enum": [
-        "default"
-      ],
-      "x-ms-parameter-location": "method"
     }
   },
   "securityDefinitions": {