chore: remove redundant execute flow mutation

packages/backend/src/graphql/schema.graphql

@@ -3,7 +3,6 @@ type Query {
 }
 type Mutation {
   createConnection(input: CreateConnectionInput): Connection
-  executeFlow(input: ExecuteFlowInput): executeFlowType
   generateAuthUrl(input: GenerateAuthUrlInput): AuthLink
   resetConnection(input: ResetConnectionInput): Connection
   updateConnection(input: UpdateConnectionInput): Connection
@@ -153,11 +152,6 @@ type ConnectionData {
   screenName: String
 }
 
-type executeFlowType {
-  data: JSONObject
-  step: Step
-}
-
 type ExecutionStep {
   id: String
   executionId: String
@@ -232,10 +226,6 @@ input VerifyConnectionInput {
   id: String!
 }
 
-input ExecuteFlowInput {
-  stepId: String!
-}
-
 input UserRoleInput {
   id: String
 }