Remove references to submodules (#11673)

This PR removes the references to initializing Git submodules as part of
building Zed.

These are no longer needed, as our only submodule was removed in #11672.

Release Notes:

- N/A

.github/workflows/publish_extension_cli.yml

@@ -19,7 +19,6 @@ jobs:
         uses: actions/checkout@v4
         with:
           clean: false
-          submodules: "recursive"
 
       - name: Cache dependencies
         uses: swatinem/rust-cache@v2