[lldb][test] TestNSDictionarySynthetic.py: adjust ptr depth in test

Fixes failure after we introduced a default limit in
#149282

We already did this test change on the Apple fork.

Author: Michael137

lldb/test/API/functionalities/data-formatter/nsdictionarysynth/TestNSDictionarySynthetic.py

@@ -2,7 +2,6 @@
 Test lldb data formatter subsystem.
 """
 
-
 import lldb
 from lldbsuite.test.decorators import *
 from lldbsuite.test.lldbtest import *
@@ -120,6 +119,8 @@ def cleanup():
                 '@"2 elements"',
             ],
         )
+
+        self.runCmd("settings set target.max-children-depth 6")
         self.expect(
             "frame variable mutabledict --ptr-depth 3",
             substrs=[