address circular reference in LazyLoader with ThreadLocalProxy

when lazyLoader was getting instantiated from inside already lazyloaded
modules (ie state), pillar/grain (and probably other) globals were
already populated. In this case they weren't getting dereferenced
properly when wrapped via the NamespacedDict wrapper, causing an
infinite loop. This should fix that scenario.

Fixes saltstack#50655 (comment)

tests/integration/files/file/base/issue-51499.sls

@@ -0,0 +1,6 @@
+{% if 'nonexistent_module.function' in salt %}
+{% do salt.log.warning("Module is available") %}
+{% endif %}
+always-passes:
+  test.succeed_without_changes:
+    - name: foo

tests/integration/modules/test_state.py

@@ -2118,3 +2118,16 @@ def test_state_sls_integer_name(self):
         self.assertEqual(state_run[state_id]['comment'],
                          'Success!')
         self.assertTrue(state_run[state_id]['result'])
+
+    def test_state_sls_lazyloader_allows_recursion(self):
+        '''
+        This tests that referencing dunders like __salt__ work
+        context: https://github.com/saltstack/salt/pull/51499
+        '''
+        state_run = self.run_function('state.sls', mods='issue-51499')
+
+        state_id = 'test_|-always-passes_|-foo_|-succeed_without_changes'
+        self.assertIn(state_id, state_run)
+        self.assertEqual(state_run[state_id]['comment'],
+                         'Success!')
+        self.assertTrue(state_run[state_id]['result'])