apex_sepolicy_tests: check apex roots are search-able

Narrow down the check for apex roots. It was 'read', but 'search' should
be enough.

Bug: 310528686
Test: m
Change-Id: Ibe5f2e948464580832d87e8d8364c33a437efed2
diff --git a/tests/apex_sepolicy_tests_test.py b/tests/apex_sepolicy_tests_test.py
index 6e719ed..3fee43d 100644
--- a/tests/apex_sepolicy_tests_test.py
+++ b/tests/apex_sepolicy_tests_test.py
@@ -96,7 +96,7 @@
         self.assert_error('./etc/linker.config.pb u:object_r:vendor_file:s0',
                         r'Error: .*linkerconfig.* can\'t read')
         self.assert_error('./ u:object_r:apex_data_file:s0',
-                        r'Error: .*linkerconfig.* can\'t read')
+                        r'Error: .*linkerconfig.* can\'t search')
 
     def test_unknown_label(self):
         self.assert_error('./bin/hw/foo u:object_r:foo_exec:s0',