[NFC][lldb][test] Fix typo in test setup commands. (llvm#137944)

Author: da-viper

lldb/packages/Python/lldbsuite/test/lldbtest.py

@@ -757,7 +757,7 @@ def getPlatformAvailablePorts(self):
     def setUpCommands(cls):
         commands = [
             # First of all, clear all settings to have clean state of global properties.
-            "settings clear -all",
+            "settings clear --all",
             # Disable Spotlight lookup. The testsuite creates
             # different binaries with the same UUID, because they only
             # differ in the debug info, which is not being hashed.