test: don't run old binaries under valgrind

This is unnecessary and caused test failures. The backward
compatibility tests are meant to find regressions in the
current codebase, not to detect bugs in older releases.

test/functional/test_framework/test_node.py

@@ -110,7 +110,8 @@ class TestNode():
         if self.descriptors is None:
             self.args.append("-disablewallet")
 
-        if use_valgrind:
+        # Use valgrind, expect for previous release binaries
+        if use_valgrind and version is None:
             default_suppressions_file = Path(__file__).parents[3] / "contrib" / "valgrind.supp"
             suppressions_file = os.getenv("VALGRIND_SUPPRESSIONS_FILE",
                                           default_suppressions_file)