fix(tests): Prevent router_test.exs from running async (#2288) #5536

Job	Run time
file_changes	3s
Build application and assets	6m 29s
Build Docker image	7m 19s
Linting / JavaScript	22s
Linting / TypeScript	36s
Unit tests / JavaScript / Mocha	36s
Linting / CSS	23s
Linting / Elixir	0s
Formatting / Elixir	3m 16s
Formatting / JavaScript & TypeScript	27s
Unit tests / JavaScript & TypeScript / Jest	2m 17s
Type checks / Elixir	3m 39s
Type checks / TypeScript	40s
Unit tests / Elixir / mix coveralls.html	1m 1s
	27m 8s

Provide feedback