Revert "ci: allow failure for ember-lts-2.4 and ember-lts-2.8"
Revert "ci: allow failure for ember-lts-2.4 and ember-lts-2.8"

This reverts commit f008a0a09bff59c5f2218088a159ca5116d76430.

lfridael/ember-cli-font-awesome,martndemus/ember-font-awesome,martndemus/ember-cli-font-awesome,martndemus/ember-cli-font-awesome,martndemus/ember-font-awesome,lfridael/ember-cli-font-awesome