Send HTTP/1.1 request instead of HTTP/2

With EnableFullDuplex() bidirectional communication works even
for HTTP/1.1

internal/command/uploadpack/git_workhorse_call.go

@@ -2,26 +2,14 @@ package uploadpack
 
 import (
 	"context"
-	"crypto/tls"
 	"io"
-	"net"
 	"net/http"
 
-	"golang.org/x/net/http2"
-
 	"gitlab.com/gitlab-org/gitlab-shell/v14/internal/command/shared/accessverifier"
 )
 
 func (c *Command) performWorkhorseCall(ctx context.Context, response *accessverifier.Response) error {
-	client := &http.Client{
-		Transport: &http2.Transport{
-			AllowHTTP: true,
-			DialTLSContext: func(ctx context.Context, network, addr string, cfg *tls.Config) (net.Conn, error) {
-				dialer := &net.Dialer{}
-				return dialer.DialContext(ctx, network, addr)
-			},
-		},
-	}
+	client := &http.Client{}
 
 	req, err := http.NewRequestWithContext(ctx, http.MethodPost, response.GitRpcUrl, io.NopCloser(c.ReadWriter.In))
 	if err != nil {