STYLE: Fix return-type alignment for clang-format 19.1.7

CI uses clang-format 19.1.7 which expects the function name
indented to align under the return type export macro. The previous
commit used clang-format 22 which un-indented it.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hjmjohnson

include/PerformanceBenchmarkingUtilities.h

@@ -22,7 +22,7 @@ using MultiThreaderName = itk::MultiThreaderBase;
 #endif
 
 PerformanceBenchmarking_EXPORT std::string
-PerfDateStamp();
+                               PerfDateStamp();
 
 PerformanceBenchmarking_EXPORT std::string
 ReplaceOccurrence(std::string str, const std::string && findvalue, const std::string && replacevalue);