fix: cut npm release only after ember-try cleanup

.travis.yml

@@ -1,6 +1,6 @@
 language: node_js
 node_js:
-  - stable
+  - 10
 
 sudo: required
 dist: trusty
@@ -45,7 +45,7 @@ script:
   - yarn lint:js
   # Usually, it's ok to finish the test scenario without reverting
   #  to the addon's original dependency state, skipping "cleanup".
-  - node_modules/.bin/ember try:one $EMBER_TRY_SCENARIO --skip-cleanup
+  - node_modules/.bin/ember try:one $EMBER_TRY_SCENARIO
 
 after_success:
   - nvm install 10