CI Optimization:Remove unused ENV variables and Skip install Step (#9632)

.travis.yml

@@ -24,8 +24,6 @@ env:
     # Dummy values needed to verify the app boots via "rails runner"
     - APP_PROTOCOL=http://
     - APP_DOMAIN=localhost:3000
-    - TIMBER=dummy
-    - SEND_LOGS_TO_TIMBER=false
     - SENDGRID_USERNAME_ACCEL=dummy
     - SENDGRID_PASSWORD_ACCEL=dummy
     - HEROKU_APP_URL=practicaldev.herokuapp.com
@@ -43,6 +41,7 @@ env:
 branches:
   only:
     - master
+install: true
 script:
   - date --rfc-3339=seconds
   - nvm install