PLT-7206: Remove the "Delete Channel" option for private channels if you're the last channel member and policy setting restricts channel deletion (#7050)

* PLT-7206: UI changes. Removed last user in channel loophole, refactored code to clean it up, added differentiated support for public and private channels, added unit tests. Still need to implement server-side checks

* PLT-7206: All helper methods in channel_utils.jsx now accept the same three boolean variables in the same order and use the same boolean logic to check their values.

* PLT-7206: Added unit tests for showManagementOptions(...)

* PLT-7206: Fixed test case descriptions

* Added unit tests for showCreateOption(...)

* PLT-7206: Added unit tests for canManageMembers(...)

* PLT-7206: Removed last person in channel loophole from server-side code

* PLT-7206: Reverted config.json

* PLT-7206: Fixed double negatives in unit test names

* PLT-7206: PR feedback - Removed confusing comment and unused variable

api4/channel.go

@@ -534,19 +534,12 @@ func deleteChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	var memberCount int64
-	if memberCount, err = app.GetChannelMemberCount(c.Params.ChannelId); err != nil {
-		c.Err = err
-		return
-	}
-
 	if channel.Type == model.CHANNEL_OPEN && !app.SessionHasPermissionToChannel(c.Session, channel.Id, model.PERMISSION_DELETE_PUBLIC_CHANNEL) {
 		c.SetPermissionError(model.PERMISSION_DELETE_PUBLIC_CHANNEL)
 		return
 	}
 
-	// Allow delete if there's only one member left in a private channel
-	if memberCount > 1 && channel.Type == model.CHANNEL_PRIVATE && !app.SessionHasPermissionToChannel(c.Session, channel.Id, model.PERMISSION_DELETE_PRIVATE_CHANNEL) {
+	if channel.Type == model.CHANNEL_PRIVATE && !app.SessionHasPermissionToChannel(c.Session, channel.Id, model.PERMISSION_DELETE_PRIVATE_CHANNEL) {
 		c.SetPermissionError(model.PERMISSION_DELETE_PRIVATE_CHANNEL)
 		return
 	}