MM-60413: Fix issues due to incorrect cache provider (#28181)

We were using a mock cache provider which mixed up LRU caches
with each other. This led to incorrect unmarshalling method calls.

We fix this by using the real cache provider.

https://mattermost.atlassian.net/browse/MM-60413

```release-note
NONE
```

server/platform/services/cache/lru_test.go

@@ -294,12 +294,12 @@ func TestLRUMarshalUnMarshal(t *testing.T) {
 	u.Timezone = nil
 	require.Equal(t, user, u)
 
-	tt := make(map[string]*model.User)
+	tt := make(model.UserMap)
 	tt["1"] = u
-	err = l.SetWithDefaultExpiry("mm", model.UserMap(tt))
+	err = l.SetWithDefaultExpiry("mm", tt)
 	require.NoError(t, err)
 
-	var out map[string]*model.User
+	var out model.UserMap
 	err = l.Get("mm", &out)
 	require.NoError(t, err)
 	out["1"].Timezone = nil