vc-dir: ensure we don't use a pager with git

* lisp/vc/vc-git.el (vc-git--call): Call git with '--no-pager' to
avoid hangs caused by remote pager settings (Bug#38688).
1 job for emacs-27 in 54 minutes and 6 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #4745
test-all

00:54:06