docs(graphql): fix deleteTest "Create"->"Delete" (datahub-project#6574)

Co-authored-by: Aseem Bansal <[email protected]>

datahub-graphql-core/src/main/resources/tests.graphql

@@ -225,7 +225,7 @@ extend type Mutation {
   updateTest(urn: String!, input: UpdateTestInput!): String
 
   """
-  Create an existing test - note that this will NOT delete dangling pointers until the next execution of the test.
+  Delete an existing test - note that this will NOT delete dangling pointers until the next execution of the test.
   """
   deleteTest(urn: String!): Boolean
-}
+}