Removed the max/min family of functions (#28679)

They are in-built in Go now
```release-note
NONE
```

server/channels/store/localcachelayer/layer.go

@@ -152,7 +152,7 @@ func NewLocalCacheLayer(baseStore store.Store, metrics einterfaces.MetricsInterf
 		DefaultExpiry:          RoleCacheSec * time.Second,
 		InvalidateClusterEvent: model.ClusterEventInvalidateCacheForRoles,
 		Striped:                true,
-		StripedBuckets:         maxInt(runtime.NumCPU()-1, 1),
+		StripedBuckets:         max(runtime.NumCPU()-1, 1),
 	}); err != nil {
 		return
 	}
@@ -336,7 +336,7 @@ func NewLocalCacheLayer(baseStore store.Store, metrics einterfaces.MetricsInterf
 		DefaultExpiry:          UserProfileByIDSec * time.Second,
 		InvalidateClusterEvent: model.ClusterEventInvalidateCacheForProfileByIds,
 		Striped:                true,
-		StripedBuckets:         maxInt(runtime.NumCPU()-1, 1),
+		StripedBuckets:         max(runtime.NumCPU()-1, 1),
 	}); err != nil {
 		return
 	}
@@ -394,13 +394,6 @@ func NewLocalCacheLayer(baseStore store.Store, metrics einterfaces.MetricsInterf
 	return
 }
 
-func maxInt(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
-
 func (s LocalCacheStore) Reaction() store.ReactionStore {
 	return s.reaction
 }

server/channels/store/sqlstore/shared_channel_store.go

@@ -818,7 +818,7 @@ func (s SqlSharedChannelStore) UpdateUserLastSyncAt(userID string, channelID str
 		return err
 	}
 
-	updateAt := maxInt64(user.UpdateAt, user.LastPictureUpdate)
+	updateAt := max(user.UpdateAt, user.LastPictureUpdate)
 
 	query := s.getQueryBuilder().
 		Update("SharedChannelUsers AS scu").

server/channels/store/sqlstore/utils.go

@@ -192,13 +192,6 @@ func trimInput(input string) string {
 	return input
 }
 
-func maxInt64(a, b int64) int64 {
-	if a > b {
-		return a
-	}
-	return b
-}
-
 // Adds backtiks to the column name for MySQL, this is required if
 // the column name is a reserved keyword.
 //