app-grid: Don't show favorites on the app list

Fixes #164
5 jobs for duplicated-favorites in 6 minutes and 59 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Build
passed #139667
librem5
build:native

00:01:38

 
  Test
passed #139669
librem5
test:smoke:one-output

00:02:10

passed #139670
librem5
test:smoke:two-outputs

00:02:07

passed #139668
librem5
unit-test:native

00:01:21

6.1%
 
  Package
passed #139671
librem5
package:deb

00:01:50