Bug#805414: gdm3: disable pulseaudio to prevent capturing A2DP sink on session start

[Tuxicoman]

Everyone who want to send audio to an bluetooth receiver will face this
issue.

Can we at least include the workaround from the wiki https://wiki.debia
n.org/BluetoothUser/a2dp

In order to prevent GDM from capturing the A2DP sink on session start,
edit /var/lib/gdm3/.config/pulse/client.conf (or create it, if it
doesn't exist):

autospawn = no
daemon-binary = /bin/true

After that you have to grant access to this file to Debian-gdm user:

# chown Debian-gdm:Debian-gdm /var/lib/gdm3/.config/pulse/client.conf