MM-55524: Include deactivated users in DM export (#25695)

We were incorrectly excluding deactivated users
while getting channel members for a DM channel, whereas
we were actually exporting all users in the users array.

We fix this and also correctly honor the includeArchivedChannels
flag as well.

https://mattermost.atlassian.net/browse/MM-55524

```release-note
Include deactivated members in a favorited DM channel export.
```


---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/store/store.go

@@ -294,7 +294,7 @@ type ChannelStore interface {
 	DeleteSidebarCategory(categoryID string) error
 	DeleteAllSidebarChannelForChannel(channelID string) error
 	GetAllChannelsForExportAfter(limit int, afterID string) ([]*model.ChannelForExport, error)
-	GetAllDirectChannelsForExportAfter(limit int, afterID string) ([]*model.DirectChannelForExport, error)
+	GetAllDirectChannelsForExportAfter(limit int, afterID string, includeArchivedChannels bool) ([]*model.DirectChannelForExport, error)
 	GetChannelMembersForExport(userID string, teamID string, includeArchivedChannel bool) ([]*model.ChannelMemberForExport, error)
 	RemoveAllDeactivatedMembers(ctx request.CTX, channelID string) error
 	GetChannelsBatchForIndexing(startTime int64, startChannelID string, limit int) ([]*model.Channel, error)