cmd/wrapper_coverage: prevent non-needed REST requests via context timeout (#1154)

* wrapper_coverage/exchanges: cancel context to not send rest requests/ populate context through functions that do rest requests

* linter: fix

* exchange_template: fix test

---------

Co-authored-by: Ryan O'Hara-Reid <ryan.oharareid@thrasher.io>

exchanges/bittrex/bittrex_test.go

@@ -57,7 +57,7 @@ func TestMain(m *testing.M) {
 	}
 
 	var wg sync.WaitGroup
-	err = b.Start(&wg)
+	err = b.Start(context.Background(), &wg)
 	if err != nil {
 		log.Fatal(err)
 	}