ci: Optimize west fetching and default to it

Using treeless clones from zmkfirmware/zmk#2757
and manifest.project-filter from https://github.com/zmkfirmware/zmk-cli/blob/main/zmk/repo.py#L253
to reduce amount of data fetched.

Remove caching since it is no longer very necessary and default to turning it on,
since it adds <10s to runtime.

.github/workflows/draw-zmk.yml

@@ -15,8 +15,8 @@ on:
         required: false
         type: string
       west_config_path:
-        description: 'Path to the folder containing west.yml, e.g. `config`. If specified, west will be initialized to fetch modules defined in west.yml'
-        default: ''
+        description: 'Path to the folder containing west.yml, e.g. `config`. Set to empty to skip fetching modules from west.yml'
+        default: 'config'
         required: false
         type: string
       output_folder:
@@ -108,32 +108,12 @@ jobs:
         if: inputs.west_config_path != ''
         run: pipx install west
 
-      - name: Cache west modules
+      - name: Fetch west modules
         if: inputs.west_config_path != ''
-        uses: actions/cache@v4
-        continue-on-error: true
-        env:
-          cache_name: cache-zephyr-3.5.0-modules
-        with:
-          path: |
-            modules/
-            tools/
-            zephyr/
-            bootloader/
-            zmk/
-          key: ${{ runner.os }}-build-${{ env.cache_name }}-${{ hashFiles('**/west.yml', '**/build.yaml') }}
-          restore-keys: |
-            ${{ runner.os }}-build-${{ env.cache_name }}-
-            ${{ runner.os }}-build-
-            ${{ runner.os }}-
-
-      - name: West Init
-        if: inputs.west_config_path != ''
-        run: west init -l ${{ inputs.west_config_path }}
-
-      - name: West Update
-        if: inputs.west_config_path != ''
-        run: west update
+        run: |
+          west init -l ${{ inputs.west_config_path }}
+          west config --local manifest.project-filter " -zmk"
+          west update --fetch-opt=--filter=tree:0
 
       - name: Draw keymaps
         id: draw