Use input files from current series of tests

As an exception to our general philosophy, we prefer here to use as
input the results from previous tests in the current series of tests
because these are performance tests that we want to try with different
sizes of edgelist. We do not want to run the tests three times to have
the performance for a new size of edgelist.

Trajectories/Tests/perf_tests.json

@@ -14,7 +14,7 @@
             "$src_dir/Trajectories/cost_function.py",
             "$my_data_dir/Global_1993_2023/SHPC",
             "Anticyclones",
-            "$tests_old_dir/Perf_segments/segments.gt",
+            "$PWD/Perf_segments/segments.gt",
             "segments_cost_functions.gt"
 	]
     },
@@ -22,7 +22,7 @@
 	"description": "Performance test with adjustable size of input.",
 	"command": [
             "$src_dir/Trajectories/trajectories.py",
-            "$tests_old_dir/Perf_cost_function/segments_cost_functions.gt"
+            "$PWD/Perf_cost_function/segments_cost_functions.gt"
 	]
     }
 }