Do not depend on boost_system's test build directory since it no longer exists.

--- libs/graph/test/Jamfile.v2.orig	2025-08-06 18:49:10 UTC
+++ libs/graph/test/Jamfile.v2
@@ -172,11 +172,9 @@ alias graph_test_with_filesystem :
 alias graph_test_with_filesystem :
     [ run all_planar_input_files_test.cpp
         ../../filesystem/build
-        ../../system/build
         : $(PLANAR_INPUT_FILES) ]
     [ run parallel_edges_loops_test.cpp
         ../../filesystem/build
-        ../../system/build
         : $(PLANAR_INPUT_FILES) ]
     ;