Enable swift only lldb tests for macOS toolchain preset

Author: shahmishal

utils/build-presets.ini

@@ -1051,7 +1051,7 @@ stress-test
 
 dash-dash
 
-skip-test-lldb
+lldb-test-swift-only
 
 # Path to the .tar.gz package we would create.
 installable-package=%(installable_package)s