config: set COSA_TESTISO_DEBUG on non-prod streams for now

We're trying to get more information on the root cause for
coreos/fedora-coreos-tracker#1796
and maybe this will help us find a clue.

Author: dustymabe

config.yaml

@@ -8,10 +8,16 @@ streams:
   testing-devel:
     type: development
     default: true
+    env:
+      COSA_TESTISO_DEBUG: true
   next-devel:         # do not touch; line managed by `next-devel/manage.py`
     type: development # do not touch; line managed by `next-devel/manage.py`
+    env:
+      COSA_TESTISO_DEBUG: true
   rawhide:
     type: mechanical
+    env:
+      COSA_TESTISO_DEBUG: true
   # branched:
   #  type: mechanical
   #  env: