Fix SSK based closed group size inconsistency

Signal/src/Loki/View Controllers/NewClosedGroupVC.swift

@@ -174,7 +174,7 @@ final class NewClosedGroupVC : BaseVC, UITableViewDataSource, UITableViewDelegat
         guard selectedContacts.count >= 1 else {
             return showError(title: "Please pick at least 1 group member")
         }
-        guard selectedContacts.count < 50 else { // Minus one because we're going to include self later
+        guard selectedContacts.count < ClosedGroupsProtocol.groupSizeLimit else { // Minus one because we're going to include self later
             return showError(title: NSLocalizedString("vc_create_closed_group_too_many_group_members_error", comment: ""))
         }
         let selectedContacts = self.selectedContacts

SignalServiceKit/src/Loki/Protocol/Closed Groups/ClosedGroupsProtocol.swift

@@ -13,6 +13,7 @@ import PromiseKit
 @objc(LKClosedGroupsProtocol)
 public final class ClosedGroupsProtocol : NSObject {
     public static let isSharedSenderKeysEnabled = false
+    public static let groupSizeLimit = 10
 
     // MARK: - Sending