Scolletd: Exit the sending loop when full

When the scollectd fills its buffer it should exist the nested loops
completely.
Curently the break only exit only the iner loop which cause the collectd
to report only partial of the metrics.

See scylladb/scylladb#2400

core/scollectd.cc

@@ -411,7 +411,8 @@ void impl::run() {
 
         out.clear();
 
-        while (m_itartor != vals->end()) {
+        bool out_of_space = false;
+        while (!out_of_space && m_itartor != vals->end()) {
             while (i != m_itartor->second.end()) {
                 if (i->type() == seastar::metrics::impl::data_type::HISTOGRAM) {
                     ++i;
@@ -421,10 +422,14 @@ void impl::run() {
                 out.put(_host, _period, std::get<seastar::metrics::impl::register_ref>(*i)->get_id(), std::get<seastar::metrics::impl::metric_value>(*i));
                 if (!out) {
                     out.reset(m);
+                    out_of_space = true;
                     break;
                 }
                 ++i;
             }
+            if (out_of_space) {
+                break;
+            }
             ++m_itartor;
             if (m_itartor != vals->end()) {
                 i = m_itartor->second.begin();