CI: Refactor build workflows to use SCONSFLAGS

.github/workflows/javascript_builds.disabled

@@ -1,9 +1,10 @@
 name: 🌐 JavaScript Builds
 on: [push, pull_request]
 
-# Global Cache Settings
+# Global Settings
 env:
   GODOT_BASE_BRANCH: master
+  SCONSFLAGS: platform=javascript verbose=yes warnings=all werror=yes --jobs=2
   SCONS_CACHE_LIMIT: 4096
   EM_VERSION: 1.39.20
   EM_CACHE_FOLDER: 'emsdk-cache'
@@ -74,7 +75,7 @@ jobs:
         env:
           SCONS_CACHE: ${{github.workspace}}/.scons_cache/
         run: |
-          scons -j2 verbose=yes warnings=all werror=yes platform=javascript target=release tools=no use_closure_compiler=yes
+          scons target=release tools=no use_closure_compiler=yes
           ls -l bin/
 
       - uses: actions/upload-artifact@v2