Added Use button on sucessful .xpshopbuy or when a user already owns the item

src/NadekoBot/Db/PostgreSqlContext.cs

@@ -8,10 +8,6 @@ public sealed class PostgreSqlContext : NadekoContext
 
     protected override string CurrencyTransactionOtherIdDefaultValue
         => "NULL";
-    protected override string DiscordUserLastXpGainDefaultValue
-        => "timezone('utc', now()) - interval '-1 year'";
-    protected override string LastLevelUpDefaultValue
-        => "timezone('utc', now())";
 
     public PostgreSqlContext(string connStr = "Host=localhost")
     {