Merge pull request #25757 from dkurt:d.kurtaev/opencv_js_tests_old_emsdk

Use onRuntimeInitialized with OpenCV.js Node tests #25757

### Pull Request Readiness Checklist

tests: https://github.com/opencv/ci-gha-workflow/pull/174

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake

modules/js/test/init_cv.js

@@ -2,13 +2,18 @@
 // It is subject to the license terms in the LICENSE file found in the top-level directory
 // of this distribution and at http://opencv.org/license.html.
 
-if (cv instanceof Promise) {
-    QUnit.test("init_cv", (assert) => {
+QUnit.test("init_cv", (assert) => {
+    if (cv instanceof Promise) {
         const done = assert.async();
-        assert.ok(true);
         cv.then((ready_cv) => {
             cv = ready_cv;
             done();
         });
-    });
-}
+    } else if (cv.getBuildInformation === undefined) {
+        const done = assert.async();
+        cv['onRuntimeInitialized'] = () => {
+            done();
+        }
+    }
+    assert.ok(true);
+});