testing/testcase: snapshot etc recursively

Everything in etc can be interesting while investigating issues in
test, also it should not be too big.

slapos/testing/testcase.py

@@ -293,14 +293,13 @@ class SlapOSInstanceTestCase(unittest.TestCase):
   _test_file_snapshot_directory = ""  # directory to save snapshot files for inspections
   # patterns of files to save for inspection, relative to instance directory
   _save_instance_file_pattern_list = (
-      'etc/supervisord.conf',
-      'etc/supervisord.conf.d/*',
       '*/bin/*',
       '*/etc/*',
       '*/var/log/*',
       '*/.*log',
       '*/.*cfg',
       '*/*cfg',
+      'etc/',
   )
 
   # Methods to be defined by subclasses.