[lldb] Skip TestSwiftTaskSwitch under older debugservers and asan.

Older debugservers incorrectly report memory region kinds for memory
allocated by the sanitizer, making swift stepping fail.

Author: felipepiovezan

lldb/test/API/lang/swift/async/stepping/step-in/task-switch/TestSwiftTaskSwitch.py

@@ -7,6 +7,7 @@
 class TestCase(lldbtest.TestBase):
     @swiftTest
     @skipIf(oslist=["windows", "linux"])
+    @skipIf(macos_version=["<", "26.0"], asan=True) # rdar://138777205
     def test(self):
         """Test conditions for async step-in."""
         self.build()