Let the snapshot wait exist in both configurations

The cases that use it are compiled in both on purpose: a case removed from the binary stays registered with CTest and reports a pass without running, so they skip in SetUp instead. Putting the helper they call behind ENABLE_ASYNC_EXPORT broke that, and six call sites failed to compile in a synchronous build.

It has a stub there now, inline so that an unused static function does not trip the maintainer mode warning ratchet. Synchronous with maintainer mode builds clean and skips what it should, asynchronous passes 28 of 28, and asynchronous with maintainer mode builds with no warnings.

Signed-off-by: thc1006 <84045975+thc1006@users.noreply.github.com>

Author: thc1006

exporters/elasticsearch/test/es_log_record_exporter_test.cc

@@ -298,6 +298,17 @@ bool WaitForWatermarks(logs_exporter::ElasticsearchLogRecordExporter &exporter,
   return false;
 }
 }  // namespace
+#else
+namespace
+{
+// The cases that call this skip in SetUp when there is no wait to observe, but they are compiled
+// in both configurations on purpose: a case removed from the binary stays registered with CTest
+// and reports a pass without running. So the helper has to exist in both too.
+inline bool WaitForWatermarks(logs_exporter::ElasticsearchLogRecordExporter &, std::uint64_t)
+{
+  return false;
+}
+}  // namespace
 #endif  // ENABLE_ASYNC_EXPORT
 
 // ---------------------------------------------------------------------------