[Bug] Typo in optional feature detection (for deprecation)

[rwjblue]

There is a typo here:

ember.js/lib/index.js

Line 146 in c1f7390

!optionalFeatures.isFeatureEnabled('template-only-glimmer-compoents')

This was introduced with #19372, and causes the following error for all addons:

TypeError: Cannot read property 'default' of undefined
    at Class.isFeatureEnabled (/home/runner/work/ember-m3/ember-m3/node_modules/@ember/optional-features/index.js:68:57)
    at Class.included (/home/runner/work/ember-m3/ember-m3/node_modules/ember-source/lib/index.js:146:27)
    at Class.superWrapper [as included] (/home/runner/work/ember-m3/ember-m3/node_modules/core-object/lib/assign-properties.js:34:20)
    at project.addons.forEach (/home/runner/work/ember-m3/ember-m3/node_modules/ember-cli/lib/broccoli/ember-app.js:634:15)
    at Array.forEach (<anonymous>)
    at EmberAddon._notifyAddonIncluded (/home/runner/work/ember-m3/ember-m3/node_modules/ember-cli/lib/broccoli/ember-app.js:632:25)
    at new EmberApp (/home/runner/work/ember-m3/ember-m3/node_modules/ember-cli/lib/broccoli/ember-app.js:138:10)
    at new EmberAddon (/home/runner/work/ember-m3/ember-m3/node_modules/ember-cli/lib/broccoli/ember-addon.js:61:5)
    at module.exports (/home/runner/work/ember-m3/ember-m3/ember-cli-build.js:31:13)
    at Builder.readBuildFile (/home/runner/work/ember-m3/ember-m3/node_modules/ember-cli/lib/models/builder.js:49:14)

(thanks to @hjdivad for the nightly CI failure detection over in ember-m3/ember-m3#999)