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/platform/services/cache/lru_striped.go

@@ -4,6 +4,7 @@
 package cache
 
 import (
+	"errors"
 	"fmt"
 	"math"
 	"time"
@@ -62,11 +63,6 @@ func (L LRUStriped) Purge() error {
 	return nil
 }
 
-// Set does the same as LRU.Set
-func (L LRUStriped) Set(key string, value any) error {
-	return L.keyBucket(key).Set(key, value)
-}
-
 // SetWithDefaultExpiry does the same as LRU.SetWithDefaultExpiry
 func (L LRUStriped) SetWithDefaultExpiry(key string, value any) error {
 	return L.keyBucket(key).SetWithDefaultExpiry(key, value)
@@ -95,16 +91,22 @@ func (L LRUStriped) Remove(key string) error {
 	return L.keyBucket(key).Remove(key)
 }
 
-// Keys does the same as LRU.Keys. However, because this is lock-free, keys might be
-// inserted or removed from a previously scanned LRU cache.
-// This is not as precise as using a single LRU instance.
-func (L LRUStriped) Keys() ([]string, error) {
-	var keys []string
-	for _, lru := range L.buckets {
-		k, _ := lru.Keys() // Keys never returns any error
-		keys = append(keys, k...)
+// RemoveMulti does the same as LRU.RemoveMulti
+func (L LRUStriped) RemoveMulti(keys []string) error {
+	var err error
+	for _, key := range keys {
+		err = errors.Join(err, L.keyBucket(key).Remove(key))
 	}
-	return keys, nil
+	return err
+}
+
+// Scan is basically a copy of Keys in LRU mode.
+// See comment in LRU.Scan.
+func (L LRUStriped) Scan(f func([]string) error) error {
+	for _, lru := range L.buckets {
+		lru.Scan(f)
+	}
+	return nil
 }
 
 // Len does the same as LRU.Len. As for LRUStriped.Keys, this call cannot be precise.