[lldb] Fix duplicate test class name causing lldb-dotest conflict (#169861)

Duplicate test class name `TestFrameVarDILPointerArithmetic` prevents
lldb-dotest from running any tests.
The conflict exists between:
- lldb/test/API/commands/frame/vardil/expr/PointerArithmetic/
- lldb/test/API/commands/frame/vardil/basics/PointerArithmetic/

Rename the expr variant to `TestFrameVarDILExprPointerArithmetic`.

Author: da-viper

lldb/test/API/commands/frame/var-dil/expr/PointerArithmetic/TestFrameVarDILPointerArithmetic.py renamed to lldb/test/API/commands/frame/var-dil/expr/PointerArithmetic/TestFrameVarDILExprPointerArithmetic.py

@@ -8,7 +8,7 @@
 from lldbsuite.test import lldbutil
 
 
-class TestFrameVarDILPointerArithmetic(TestBase):
+class TestFrameVarDILExprPointerArithmetic(TestBase):
     NO_DEBUG_INFO_TESTCASE = True
 
     def test_pointer_arithmetic(self):