device-monitor: list hidden providers before listing devices

The way it was implemented could make the list updated after the
list of device was filled with supposdely hidden devices
21 jobs for device_monitor in 59 minutes and 12 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Preparation
passed #347850
gst indent

00:00:32

passed #347849
manifest

00:00:40

 
  Build
passed #347851
build fedora x86_64

00:12:33

passed #347852
build nodebug fedora x86_64

00:11:56

passed #347853
build static fedora x86_64

00:16:38

passed #347854
build static nodebug fedora x86_64

00:15:04

 
  Test
passed #347855
check fedora

00:03:30

passed #347856
integration testsuites fedora

00:08:36

 
  Full Builds
passed #347858
build cerbero android universal

00:20:40

passed #347859
build cerbero cross win32

00:14:24

passed #347860
build cerbero cross win64

00:11:44

passed #347857
build cerbero fedora x86_64

00:10:31

passed #347861
gst-macos-10.14
build cerbero macos x86_64

00:07:53

 
  Full Tests
passed #347866
valgrind bad

00:11:00

passed #347863
valgrind base

00:12:12

passed #347862
valgrind core

00:12:35

failed #347867
valgrind ges

00:08:36

passed #347864
valgrind good

00:12:35

passed #347865
valgrind ugly

00:02:49

 
  Apps
skipped #347868
android universal examples
 
  Deploy
skipped #347869
documentation
 
Name Stage Failure
failed
valgrind ges Full Tests
           Total: 98
Uploading artifacts...
gst-build/build/meson-logs/: found 2 matching files
validate-logs: found 223 matching files
Uploading artifacts to coordinator... ok id=347867 responseStatus=201 Created token=1srQpfbQ
Uploading artifacts...
validate-logs/*.xml: found 1 matching files
Uploading artifacts to coordinator... ok id=347867 responseStatus=201 Created token=1srQpfbQ
ERROR: Job failed: exit code 1