Goodbye, GraphQL (#24827)

```release-note
NONE
```

server/channels/api4/apitestlib.go

@@ -4,9 +4,7 @@
 package api4
 
 import (
-	"bytes"
 	"context"
-	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
@@ -21,7 +19,6 @@ import (
 	"time"
 
 	"github.com/gorilla/websocket"
-	graphql "github.com/graph-gophers/graphql-go"
 	s3 "github.com/minio/minio-go/v7"
 	"github.com/minio/minio-go/v7/pkg/credentials"
 	"github.com/stretchr/testify/require"
@@ -47,7 +44,6 @@ type TestHelper struct {
 
 	Context              *request.Context
 	Client               *model.Client4
-	GraphQLClient        *graphQLClient
 	BasicUser            *model.User
 	BasicUser2           *model.User
 	TeamAdminUser        *model.User
@@ -196,7 +192,6 @@ func setupTestHelper(dbStore store.Store, searchEngine *searchengine.Broker, ent
 	}
 
 	th.Client = th.CreateClient()
-	th.GraphQLClient = newGraphQLClient(fmt.Sprintf("http://localhost:%v", th.App.Srv().ListenAddr.Port))
 	th.SystemAdminClient = th.CreateClient()
 	th.SystemManagerClient = th.CreateClient()
 
@@ -811,16 +806,10 @@ func (th *TestHelper) CreateDmChannel(user *model.User) *model.Channel {
 
 func (th *TestHelper) LoginBasic() {
 	th.LoginBasicWithClient(th.Client)
-	if os.Getenv("MM_FEATUREFLAGS_GRAPHQL") == "true" {
-		th.LoginBasicWithGraphQL()
-	}
 }
 
 func (th *TestHelper) LoginBasic2() {
 	th.LoginBasic2WithClient(th.Client)
-	if os.Getenv("MM_FEATUREFLAGS_GRAPHQL") == "true" {
-		th.LoginBasicWithGraphQL()
-	}
 }
 
 func (th *TestHelper) LoginTeamAdmin() {
@@ -842,13 +831,6 @@ func (th *TestHelper) LoginBasicWithClient(client *model.Client4) {
 	}
 }
 
-func (th *TestHelper) LoginBasicWithGraphQL() {
-	_, _, err := th.GraphQLClient.login(th.BasicUser.Email, th.BasicUser.Password)
-	if err != nil {
-		panic(err)
-	}
-}
-
 func (th *TestHelper) LoginBasic2WithClient(client *model.Client4) {
 	_, _, err := client.Login(context.Background(), th.BasicUser2.Email, th.BasicUser2.Password)
 	if err != nil {
@@ -1301,22 +1283,3 @@ func (th *TestHelper) SetupScheme(scope string) *model.Scheme {
 	}
 	return scheme
 }
-
-func (th *TestHelper) MakeGraphQLRequest(input *graphQLInput) (*graphql.Response, error) {
-	url := fmt.Sprintf("http://localhost:%v", th.App.Srv().ListenAddr.Port) + model.APIURLSuffixV5 + "/graphql"
-
-	buf, err := json.Marshal(input)
-	if err != nil {
-		panic(err)
-	}
-
-	resp, err := th.GraphQLClient.doAPIRequest("POST", url, bytes.NewReader(buf), map[string]string{})
-	if err != nil {
-		panic(err)
-	}
-	defer closeBody(resp)
-
-	var gqlResp *graphql.Response
-	err = json.NewDecoder(resp.Body).Decode(&gqlResp)
-	return gqlResp, err
-}