gh-146376: Reduce timeout in Emscripten GHA workflow (GH-146378)

(cherry picked from commit 70d1b08)

Co-authored-by: Hood Chatham <roberthoodchatham@gmail.com>

Author: hoodmane

.github/workflows/reusable-emscripten.yml

@@ -10,7 +10,7 @@ jobs:
   build-emscripten-reusable:
     name: 'build and test'
     runs-on: ubuntu-24.04
-    timeout-minutes: 60
+    timeout-minutes: 40
     steps:
     - uses: actions/checkout@v6
       with: