Don't spam the echo area and the *Messages* buffer in Tramp

* lisp/net/tramp-sh.el (tramp-sh-handle-vc-registered):
When called during `revert-buffer', don't spam the echo area and
the *Messages* buffer.
2 jobs for master in 65 minutes and 14 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #4478
test-all

01:05:14

passed #4479
test-filenotify-gio

00:43:25

 
Name Stage Failure
failed
test-all Test
Makefile:319: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:294: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:959: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1