tests: Added tests for fallback to log files

Signed-off-by: Joe MacMahon <joe.macmahon@cern.ch>
actions: Added fallback log config and functionality.

Signed-off-by: Joe MacMahon <joe.macmahon@cern.ch>
docs: Added fallback log file config option.

Signed-off-by: Joe MacMahon <joe.macmahon@cern.ch>