Simplify testcase to use v instead of p (NFC)

lldb/test/API/commands/process/attach/TestProcessAttach.py

@@ -106,7 +106,7 @@ class ProcessAttachTestCase(TestBase):
         lldbutil.run_break_set_by_file_and_line(
             self, "main.cpp", self.line, num_expected_locations=1, loc_exact=False)
         self.runCmd("process continue")
-        self.expect("p g_val", substrs=["$0 = 12345"])
+        self.expect("v g_val", substrs=["12345"])
 
     def tearDown(self):
         # Destroy process before TestBase.tearDown()