Travis: Remove debug run from after_failure

It's not actually helping us diagnose the errors that we're seeing.
(--allow-failures is pretty good for that.)

Part of 30066.

.travis.yml

@@ -191,9 +191,6 @@ after_failure:
   #- cat net/nodes/00*a*/state
   - for f in net/nodes/00*a*/v3-status-votes ; do echo "$f"; cat "$f"; done
   - for f in net/nodes/00*a*/unparseable-descs/* ; do echo "$f"; cat "$f"; done
-  ## Re-run chutney in debug mode
-  ## TODO: improve debug mode
-  - tools/test-network.sh --debug && echo "chutney debug run succeeded"
 
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