[GH] Github workflow fixes

Fix incorrect syntax and migrate to actions v4

- The existing version we use (v2) now automatically fails builds / workflows, so we are being forced to migrate.
- A few playground settings.gradle files were applying the ndk.gradle file incorrectly.

Test: GH workflows (tested on dlam/androidx)

This is an imported pull request from https://github.com/androidx/androidx/pull/699.

Resolves #699
Github-Pr-Head-Sha: 03429a53019c780152bcbc533b71e134ee315dbd
GitOrigin-RevId: 5c06c99070c28d7729d9093a41eabd8bc280fd2e
Change-Id: I596f65c6332c3cc4fd930d2f9ccc27d6de6ba5f7
diff --git a/playground-projects/activity-playground/settings.gradle b/playground-projects/activity-playground/settings.gradle
index 26fdaa6..f139d27 100644
--- a/playground-projects/activity-playground/settings.gradle
+++ b/playground-projects/activity-playground/settings.gradle
@@ -23,7 +23,7 @@
     id "com.android.settings" version "8.7.0-alpha02"
 }
 
-apply ../../buildSrc/ndk.gradle
+apply from: "../../buildSrc/ndk.gradle"
 
 rootProject.name = "activity-playground"