Remove some uses of printf_unfiltered

Remove some uses of printf_unfiltered

A number of spots call printf_unfiltered only because they are in code
that should not be interrupted by the pager.  However, I believe these
cases are all handled by infrun's blanket ban on paging, and so can be
converted to the default (_filtered) API.

After this patch, I think all the remaining _unfiltered calls are ones
that really ought to be.  A few -- namely in complete_command -- could
be replaced by a scoped assignment to pagination_enabled, but for the
remainder, the code seems simple enough like this.