Revert "Update firmware_build.yml"

This reverts commit bf3c43209edbdf3aedf74056893e07ebb84159f7.

.github/workflows/firmware_build.yml

@@ -8,9 +8,9 @@ on:
 jobs:
   build_firmware:
     name: RHC-internal-Z4
-    runs-on: self-hosted
+#    runs-on: self-hosted
     name: Build firmware on GitHub using latest Ubuntu
-#    runs-on: ubuntu-latest
+    runs-on: ubuntu-latest
     
     steps:
       - name: Check out code from GitHub