Removed pallet::getter usage from pallet-collective (#3456)

Part of #3326 
This one is easier as all the storage items are public. 

@ggwpez @kianenigma @shawntabrizi

---------

Signed-off-by: Matteo Muraca <mmuraca247@gmail.com>
Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>
Co-authored-by: command-bot <>
Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

prdoc/pr_3456.prdoc

@@ -0,0 +1,15 @@
+# Schema: Polkadot SDK PRDoc Schema (prdoc) v1.0.0
+# See doc at https://raw.githubusercontent.com/paritytech/polkadot-sdk/master/prdoc/schema_user.json
+
+title: Removed `pallet::getter` usage from `pallet-collective`
+
+doc:
+  - audience: Runtime Dev
+    description: |
+      This PR removes `pallet::getter` usage from `pallet-collective`, and updates dependant code accordingly.
+      The syntax `StorageItem::<T, I>::get()` should be used instead.
+
+crates: 
+  - name: pallet-collective
+  - name: kitchensink-runtime
+  - name: collectives-westend-runtime