pw_bluetooth_sapphire: Fix BrEdrConnectionManager.Inspect test

Somehow an inspect property matcher was removed from the
BrEdrConnectionManager.Inspect test. This CL restores that matcher,
fixing this test suite when it is run on Fuchsia.

Bug: 136961
Test: (Fuchsia) fx test bt-host-gap-tests
Change-Id: I2fbcd60a32e8001df68f229aacadf305226eba06
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/183304
Pigweed-Auto-Submit: Ben Lawson <benlawson@google.com>
Reviewed-by: Ali Saeed <saeedali@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed-service-accounts.iam.gserviceaccount.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>

pw_bluetooth_sapphire/host/gap/bredr_connection_manager_test.cc

@@ -4785,7 +4785,8 @@ TEST_F(BrEdrConnectionManagerTest, Inspect) {
                             UintIs("disconnect_local_api_request_count", 1),
                             UintIs("disconnect_pairing_failed_count", 0),
                             UintIs("disconnect_peer_disconnection_count", 0),
-                            UintIs("interrogation_complete_count", 1))))),
+                            UintIs("interrogation_complete_count", 1),
+                            StringIs("security_mode", "Mode 4"))))),
       ChildrenMatch(
           UnorderedElementsAre(empty_requests_matcher,
                                connections_after_disconnect_matcher,