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/service.go

@@ -11,6 +11,7 @@ import (
 	"runtime"
 	"sync"
 	"sync/atomic"
+	"time"
 
 	"github.com/mattermost/mattermost/server/public/model"
 	"github.com/mattermost/mattermost/server/public/plugin"
@@ -293,16 +294,21 @@ func New(sc ServiceConfig, options ...Option) (*PlatformService, error) {
 	}
 
 	// Needed before loading license
-	ps.statusCache, err = cache.NewProvider().NewCache(&cache.CacheOptions{
+	ps.statusCache, err = ps.cacheProvider.NewCache(&cache.CacheOptions{
 		Name:           "Status",
 		Size:           model.StatusCacheSize,
 		Striped:        true,
 		StripedBuckets: maxInt(runtime.NumCPU()-1, 1),
+		DefaultExpiry:  30 * time.Minute,
 	})
 	if err != nil {
 		return nil, fmt.Errorf("unable to create status cache: %w", err)
 	}
 
+	// Note: we hardcode the session cache to LRU because the session invalidation
+	// path always iterates through the entire cache, leading to a lot of SCAN calls
+	// in case of Redis. We could potentially have a reverse mapping of userIDs to
+	// session IDs, but leaving this one for now.
 	ps.sessionCache, err = cache.NewProvider().NewCache(&cache.CacheOptions{
 		Name:           "Session",
 		Size:           model.SessionCacheSize,