Drop unused EthSpec generic from Stores (#9281)

Co-Authored-By: dapplion <35266934+dapplion@users.noreply.github.com>

consensus/fork_choice/tests/tests.rs

@@ -79,7 +79,7 @@ impl ForkChoiceTest {
     /// Get a value from the `ForkChoice` instantiation.
     fn get<T, U>(&self, func: T) -> U
     where
-        T: Fn(&BeaconForkChoiceStore<E, MemoryStore<E>, MemoryStore<E>>) -> U,
+        T: Fn(&BeaconForkChoiceStore<E, MemoryStore, MemoryStore>) -> U,
     {
         func(
             self.harness