Fix dexopt_test now that '&' is not a valid class loader context.

Test: installd_dexopt_test
Bug: 183975447
Change-Id: I9e66c17db66c5bd7e25eba87e38d758460a1af0f
diff --git a/cmds/installd/tests/installd_dexopt_test.cpp b/cmds/installd/tests/installd_dexopt_test.cpp
index fbf1e0c..6e1757e 100644
--- a/cmds/installd/tests/installd_dexopt_test.cpp
+++ b/cmds/installd/tests/installd_dexopt_test.cpp
@@ -351,7 +351,7 @@
             uid = kTestAppUid;
         }
         if (class_loader_context == nullptr) {
-            class_loader_context = "&";
+            class_loader_context = "PCL[]";
         }
         int32_t dexopt_needed = 0;  // does not matter;
         std::optional<std::string> out_path; // does not matter