Fix imenu menu when we're auto-refreshing

* lisp/imenu.el (imenu--make-index-alist): Don't add a *Refresh*
item if we're auto-refreshing (bug#30449).
1 job for master in 73 minutes and 57 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Test
passed #3323
test-all

01:13:57