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/app/platform/config_test.go

@@ -126,7 +126,7 @@ func TestIsFirstUserAccount(t *testing.T) {
 	}
 
 	// create a session, this should not affect IsFirstUserAccount
-	th.Service.sessionCache.Set("mock_session", 1)
+	th.Service.sessionCache.SetWithDefaultExpiry("mock_session", 1)
 
 	for _, te := range tests {
 		t.Run(te.name, func(t *testing.T) {