DEV: removes unused components (#22497)

Removes the following components which are not used anymore:
- d-progress-bar
- on-visibility-action

plugins/chat/test/javascripts/components/on-visibility-action-test.js

@@ -1,31 +0,0 @@
-import { setupRenderingTest } from "discourse/tests/helpers/component-test";
-import hbs from "htmlbars-inline-precompile";
-import { render, waitUntil } from "@ember/test-helpers";
-import { module, test } from "qunit";
-
-module("Discourse Chat | Component | on-visibility-action", function (hooks) {
-  setupRenderingTest(hooks);
-
-  test("Calling an action on visibility gained", async function (assert) {
-    this.set("value", null);
-    this.set("display", false);
-    this.set("action", () => {
-      this.set("value", "foo");
-    });
-
-    this.set("root", document.querySelector("#ember-testing"));
-
-    await render(hbs`
-      {{#if display}}
-        <OnVisibilityAction @action={{this.action}} @root={{this.root}} />
-      {{/if}}
-    `);
-
-    assert.strictEqual(this.value, null);
-
-    this.set("display", true);
-    await waitUntil(() => this.value !== null);
-
-    assert.strictEqual(this.value, "foo");
-  });
-});