MM-59932: Migrate remaining caches to Redis (#27880)

- We introduce 2 new APIs:
1. Scan: this allows incremental iteration
without blocking the Redis server and is the
recommended way to iterate over keys. With this,
we have entirely removed the need for Keys.
2. RemoveMulti: this allows deletion of multiple
keys in a single operation which optimizes
network round trips.

- While here, we make a small improvement to
GetStatusFromCache, where we remove the shallow
copy which wasn't necessary because we always
serialize the data from the cache.
- We do not use Redis for session cache because of
frequent requests to iterate the entire cache which leads
to a lot of `SCAN` calls.
- Avoid broadcasting status update messages for Redis case.
- Setting cache expiry for status cache
- Removing .Set method altogether to prevent
any chances of setting an item with no expiry.

https://mattermost.atlassian.net/browse/MM-59932

```release-note
NONE
```

server/channels/store/localcachelayer/role_layer.go

@@ -78,9 +78,9 @@ func (s LocalCacheRoleStore) GetByNames(names []string) ([]*model.Role, error) {
 			gotRole := *(toPass[i].(**model.Role))
 			if gotRole != nil {
 				foundRoles = append(foundRoles, gotRole)
-			} else {
-				s.rootStore.logger.Warn("Found nil role in GetByNames. This is not expected")
+				continue
 			}
+			s.rootStore.logger.Warn("Found nil role in GetByNames. This is not expected")
 		}
 	}