UnpackSts: Reserve memory in output vector.

algo/detectors/sts/UnpackSts.cxx

@@ -47,6 +47,9 @@ namespace cbm::algo
       return result;
     }
 
+    const u32 maxDigis = numMessages - 2;  // -2 for the TS_MSB and EPOCH messages
+    result.first.reserve(maxDigis);
+
     // --- Interpret MS content as sequence of SMX messages
     auto message = reinterpret_cast<const stsxyter::Message*>(msContent);