Revert "Remove sleep that appears to no longer be needed"

This reverts commit 6e8481bfff.

See gh-48049

module/spring-boot-jersey/src/test/java/org/springframework/boot/jersey/autoconfigure/metrics/JerseyServerMetricsAutoConfigurationTests.java

@@ -84,6 +84,7 @@ class JerseyServerMetricsAutoConfigurationTests {
 	void httpRequestsAreTimed() {
 		this.webContextRunner.withUserConfiguration(MetricsConfiguration.class).run((context) -> {
 			doRequest(context);
+			Thread.sleep(500);
 			MeterRegistry registry = context.getBean(MeterRegistry.class);
 			Timer timer = registry.get("http.server.requests").tag("uri", "/users/{id}").timer();
 			assertThat(timer.count()).isOne();