devicemonitor: Stop only the already started providers

If a device provider fails to start (for instance the pulseaudio provider unable
to connect to the PulseAudio daemon) then the monitor should not keep track of
it in its `started` providers list. Otherwise a false positive critical warning
would be raised.

This patch also switches the started_count type from bool to int, for
consistency. This is a counter, after all.

API: gst_device_provider_is_started
35 jobs for !679 with device-provider-no-stop-critical in 3 minutes and 22 seconds (queued for 3 seconds)
detached
Status Job ID Name Coverage
  Build Docker
passed #5112852
alpine amd64 manifest builder docker

00:00:28

passed #5112851
android docker

00:01:40

passed #5112850
cerbero fedora amd64 docker

00:02:47

passed #5112849
fedora amd64 docker

00:02:26

passed #5112853
gst-indent amd64 docker

00:00:35

 
  Preparation
passed #5112855
gst indent

00:00:35

manual #5112854
manual
manifest
 
  Build
created #5112864
gstreamer
build cerbero cross-android universal
created #5112868
gst-ios-13.2
build cerbero cross-ios universal
created #5112865
gstreamer
build cerbero cross win32
created #5112866
gstreamer
build cerbero cross win64
created #5112863
gstreamer
build cerbero fedora x86_64
created #5112867
gst-macos-10.15
build cerbero macos x86_64
created #5112869
1809 gstreamer-windows windows docker
build cerbero msvc x86_64
created #5112859
build clang fedora x86_64
created #5112862
1809 windows docker allowed to fail manual
build msys2
created #5112856
build nodebug fedora x86_64
created #5112857
build static fedora x86_64
created #5112858
build static nodebug fedora x86_64
created #5112860
1809 windows docker
build vs2017 amd64
created #5112861
1809 windows docker
build vs2017 x86
 
  Test
created #5112870
gstreamer
check fedora
created #5112871
gstreamer
integration testsuites fedora 1/4
created #5112872
gstreamer
integration testsuites fedora 2/4
created #5112873
gstreamer
integration testsuites fedora 3/4
created #5112874
gstreamer
integration testsuites fedora 4/4
created #5112879
gstreamer
valgrind bad
created #5112876
gstreamer
valgrind base
created #5112875
gstreamer
valgrind core
created #5112880
gstreamer
valgrind ges
created #5112877
gstreamer
valgrind good
created #5112878
gstreamer
valgrind ugly
 
  Integrate
created #5112881
cross-android universal examples
created #5112883
gst-ios-13.2
cross-ios universal examples
created #5112882
documentation