cleanup: remove unused function and resolve warning (#2350)

Signed-off-by: Mike Schore <mike.schore@gmail.com>
Signed-off-by: JP Simard <jp@jpsim.com>

mobile/library/objective-c/EnvoyEngineImpl.m

@@ -335,20 +335,6 @@ static void ios_http_filter_set_response_callbacks(envoy_http_filter_callbacks c
   }
 }
 
-static void ios_http_filter_on_complete(envoy_stream_intel stream_intel,
-                                        envoy_final_stream_intel final_stream_intel,
-                                        const void *context) {
-  // This code block runs inside the Envoy event loop. Therefore, an explicit autoreleasepool block
-  // is necessary to act as a breaker for any Objective-C allocation that happens.
-  @autoreleasepool {
-    EnvoyHTTPFilter *filter = (__bridge EnvoyHTTPFilter *)context;
-    if (filter.onComplete == nil) {
-      return;
-    }
-    filter.onComplete(stream_intel, final_stream_intel);
-  }
-}
-
 static void ios_http_filter_on_cancel(envoy_stream_intel stream_intel,
                                       envoy_final_stream_intel final_stream_intel,
                                       const void *context) {