Fix off-by-one in userspace metric writer

Index 0 in the counter_collection is reserved for the metric leader.
However userspace metrics dont have a metric leader, so start counting
the events from 1 instead of 0

src/perf/counter/userspace/writer.cpp

@@ -52,7 +52,7 @@ bool Writer::handle(std::vector<UserspaceReadFormat>& data)
 
     for (std::size_t i = 0; i < counter_buffer_.size(); i++)
     {
-        values[i] = counter_buffer_[i] * counter_collection_.get_scale(i);
+        values[i] = counter_buffer_[i] * counter_collection_.get_scale(i + 1);
     }
 
     writer_.write(metric_event_);