Remove a test-only method from base MTRDeviceController. (#35944)

This is only used with concrete controllers from tests, and is already
implemented by MTRDeviceController_Concrete.

Also removes a test-only class method from MTRDeviceController_Concrete that
MTRDeviceController already implements (and has to keep implementing, since the
tests use it on MTRDeviceController itself, not an instance).

src/darwin/Framework/CHIP/MTRDeviceController.mm

@@ -441,18 +441,6 @@ - (void)removeDevice:(MTRDevice *)device
     }
 }
 
-#ifdef DEBUG
-- (NSDictionary<NSNumber *, NSNumber *> *)unitTestGetDeviceAttributeCounts
-{
-    std::lock_guard lock(*self.deviceMapLock);
-    NSMutableDictionary<NSNumber *, NSNumber *> * deviceAttributeCounts = [NSMutableDictionary dictionary];
-    for (NSNumber * nodeID in _nodeIDToDeviceMap) {
-        deviceAttributeCounts[nodeID] = @([[_nodeIDToDeviceMap objectForKey:nodeID] unitTestAttributeCount]);
-    }
-    return deviceAttributeCounts;
-}
-#endif
-
 - (BOOL)setOperationalCertificateIssuer:(nullable id<MTROperationalCertificateIssuer>)operationalCertificateIssuer
                                   queue:(nullable dispatch_queue_t)queue
 {

src/darwin/Framework/CHIP/MTRDeviceController_Concrete.mm

@@ -1679,15 +1679,6 @@ - (nullable NSNumber *)neededReadPrivilegeForClusterID:(NSNumber *)clusterID att
     return nil;
 }
 
-#ifdef DEBUG
-+ (void)forceLocalhostAdvertisingOnly
-{
-    auto interfaceIndex = chip::Inet::InterfaceId::PlatformType(kDNSServiceInterfaceIndexLocalOnly);
-    auto interfaceId = chip::Inet::InterfaceId(interfaceIndex);
-    chip::app::DnssdServer::Instance().SetInterfaceId(interfaceId);
-}
-#endif // DEBUG
-
 @end
 
 /**