Revert "DEV: enforces ember-template-lint: no-triple-curlies (#9150)"

This reverts commit d436b600fba4cea846a5e96c235c507441965e05.

Triple curlies are still necessary for some raw templates.

test/javascripts/components/html-safe-helper-test.js.es6

@@ -1,14 +0,0 @@
-import componentTest from "helpers/component-test";
-moduleForComponent("html-safe-helper", { integration: true });
-
-componentTest("default", {
-  template: "{{html-safe string}}",
-
-  beforeEach() {
-    this.set("string", "<p class='cookies'>biscuits</p>");
-  },
-
-  async test(assert) {
-    assert.ok(exists("p.cookies"), "it displays the string as html");
-  }
-});