Refactor[BMQT]: make Subscription rule-of-three complaint (#370)

Signed-off-by: Evgeny Malygin <emalygin@bloomberg.net>

src/groups/bmq/bmqt/bmqt_subscription.h

@@ -197,16 +197,9 @@ class Subscription {
 
   public:
     // CREATORS
+    /// Create a new Subscription
     Subscription();
 
-    // Create a new Subscription
-
-    /// Create a new Subscription by copying values from the specified
-    /// `other`.
-    Subscription(const Subscription& other);
-
-    // MANIPULATORS
-
     /// Set the maxUnconfirmedMessages to the specified `value`.  The
     /// behavior is undefined unless `value >= 0`. If the specified `value`
     /// is set to 0, it means that the consumer does not receive any
@@ -276,9 +269,9 @@ bsl::ostream& operator<<(bsl::ostream& stream, const Subscription& rhs);
 //                             INLINE DEFINITIONS
 // ============================================================================
 
-// ----------------------
+// -------------------------
 // class Subscription_Handle
-// ----------------------
+// -------------------------
 
 inline SubscriptionHandle::SubscriptionHandle()
 : d_id(k_INVALID_HANDLE_ID)
@@ -385,9 +378,9 @@ inline bsl::ostream& SubscriptionExpression::print(bsl::ostream& stream,
     return stream;
 }
 
-// ----------------------
+// ------------------
 // class Subscription
-// ----------------------
+// ------------------
 
 inline Subscription::Subscription()
 : d_maxUnconfirmedMessages()
@@ -398,15 +391,6 @@ inline Subscription::Subscription()
     // NOTHING
 }
 
-inline Subscription::Subscription(const Subscription& other)
-: d_maxUnconfirmedMessages(other.d_maxUnconfirmedMessages)
-, d_maxUnconfirmedBytes(other.d_maxUnconfirmedBytes)
-, d_consumerPriority(other.d_consumerPriority)
-, d_expression(other.d_expression)
-{
-    // NOTHING
-}
-
 inline bsl::ostream&
 Subscription::print(bsl::ostream& stream, int level, int spacesPerLevel) const
 {