Test failure: com.linecorp.armeria.server.ServerBuilderTest.contextHo…

…ok() (#5877)

Motivation:

#5769 

Modifications:

- Added tearDown method with `@AfterEach` in order to reset each count variables used in tests

When executing this test in my local env, this test succeeded and I wasn't sure why this test failure was caused.
But, after adding this tearDown method, we will be able to avoid inappropriate variables staying  in cnt variables.

Result:

- Closes #5769 
- `Test failure: com.linecorp.armeria.server.ServerBuilderTest.contextHook()` will be resolved.

core/src/test/java/com/linecorp/armeria/server/ServerBuilderTest.java

@@ -37,6 +37,7 @@
 import java.util.function.Supplier;
 
 import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.RegisterExtension;
@@ -143,6 +144,13 @@ private static Server newServerWithKeepAlive(long idleTimeoutMillis, long pingIn
  .build();
  }
 
+ @AfterEach
+ void tearDown() {
+ poppedRouterCnt.set(0);
+ poppedRouterCnt2.set(0);
+ poppedCnt.set(0);
+ }
+
  @Test
  void acceptDuplicatePort() throws Exception {
  final Server server = Server.builder()