EAE local transcoding workaround, change logdir

[petetomasik]

Discovered that plexmediaserver will fall back to using the transcode directory if it gets a Permission Denied error when writing to /tmp/pms-*/ at service startup:

<TRANSCODE_DIR>/Transcode/Sessions/EasyAudioEncoder

To take advantage of this, the plex user needs to have write access to /tmp removed. This can be accomplished with:

setfacl -m u:plex:r /tmp/

With /tmp unable to be written to by the plex user, the default config for logging filename needs to be somewhere the plex user has write access (this uses /opt/plex/tmp/prt.log, matching the shared transcode directory in the wiki).

I have this working with Ubuntu 18.04 x64 master/slaves and PMS 1.13.9.5439-7303bc002 with EAE transcodes being executed on any host (including remote slaves).