Refactor git command context & pipeline (#36406)

Less and simpler code, fewer bugs

routers/web/repo/githttp.go

@@ -447,9 +447,9 @@ func serviceRPC(ctx *context.Context, service string) {
 	if err := gitrepo.RunCmdWithStderr(ctx, h.getStorageRepo(), cmd.AddArguments(".").
 		WithEnv(append(os.Environ(), h.environ...)).
 		WithStdin(reqBody).
-		WithStdout(ctx.Resp).
-		WithUseContextTimeout(true)); err != nil {
-		if !git.IsErrCanceledOrKilled(err) {
+		WithStdout(ctx.Resp),
+	); err != nil {
+		if !gitcmd.IsErrorCanceledOrKilled(err) {
 			log.Error("Fail to serve RPC(%s) in %s: %v", service, h.getStorageRepo().RelativePath(), err)
 		}
 	}