Bring back embroider scenarios

Do not transpile for `IE11` (in CI or production).

See embroider-build/embroider#731

Author: Robert Jackson

.github/workflows/build.yml

@@ -26,8 +26,8 @@ jobs:
           - ember-canary
           - ember-lts-3.16
           - ember-lts-3.20
-          # - embroider-safe
-          # - embroider-optimized
+          - embroider-safe
+          - embroider-optimized
 
     steps:
       - name: Checkout

tests/dummy/config/targets.js

@@ -6,13 +6,6 @@ const browsers = [
   'last 1 Safari versions',
 ];
 
-const isCI = Boolean(process.env.CI);
-const isProduction = process.env.EMBER_ENV === 'production';
-
-if (isCI || isProduction) {
-  browsers.push('ie 11');
-}
-
 module.exports = {
   browsers,
   node: 'current',