teamcity: add missing test count output

src/Logging/TeamCity/Converter.php

@@ -166,6 +166,14 @@ final class Converter
         return $this->toRelativePath($path);
     }
 
+    /**
+     * Gets the test suite size.
+     */
+    public function getTestSuiteSize(TestSuite $testSuite): int
+    {
+        return $testSuite->count();
+    }
+
     /**
      * Transforms the given path in relative path.
      */