Do not throw NPE in AfterAll interceptor if application didn't start

[gsmet]

This is to solve an issue that we can see from time to time in the CI:

java.lang.NullPointerException: Cannot invoke "io.quarkus.bootstrap.app.RunningQuarkusApplication.getClassLoader()" because "io.quarkus.test.junit.QuarkusTestExtension.runningQuarkusApplication" is null
	at io.quarkus.test.junit.QuarkusTestExtension.runExtensionMethod(QuarkusTestExtension.java:909)
	at io.quarkus.test.junit.QuarkusTestExtension.runExtensionMethod(QuarkusTestExtension.java:901)
	at io.quarkus.test.junit.QuarkusTestExtension.interceptAfterAllMethod(QuarkusTestExtension.java:895)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
	at java.base/java.util.Collections$UnmodifiableCollection.forEach(Collections.java:1116)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
	Suppressed: org.opentest4j.TestAbortedException: Boot failed

For instance here:
#43448 (comment) in the io.quarkus.it.mongodb.BookResourceTest failure.

Created as draft to get a full CI run.

[gsmet]

CI was green in my fork so this is now ready for review.

[quarkus-bot]

Status for workflow Quarkus CI

This is the status report for running Quarkus CI on commit 96b0c2f.

✅ The latest workflow run for the pull request has completed successfully.

It should be safe to merge provided you have a look at the other checks in the summary.

You can consult the Develocity build scans.

---

Flaky tests - Develocity

⚙️ JVM Tests - JDK 17 Windows

📦 extensions/opentelemetry/deployment

✖ io.quarkus.opentelemetry.deployment.metrics.HttpServerMetricsTest.collectsHttpRouteFromEndAttributes - History

• Assertion condition defined as a Lambda expression in io.quarkus.opentelemetry.deployment.common.exporter.InMemoryMetricExporter expected: <true> but was: <false> within 5 seconds. - org.awaitility.core.ConditionTimeoutException

org.awaitility.core.ConditionTimeoutException: Assertion condition defined as a Lambda expression in io.quarkus.opentelemetry.deployment.common.exporter.InMemoryMetricExporter expected: <true> but was: <false> within 5 seconds.
	at org.awaitility.core.ConditionAwaiter.await(ConditionAwaiter.java:167)
	at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:119)
	at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:31)
	at org.awaitility.core.ConditionFactory.until(ConditionFactory.java:1006)
	at org.awaitility.core.ConditionFactory.untilAsserted(ConditionFactory.java:790)
	at io.quarkus.opentelemetry.deployment.common.exporter.InMemoryMetricExporter.assertCountPointsAtLeast(InMemoryMetricExporter.java:131)
	at io.quarkus.opentelemetry.deployment.common.exporter.InMemoryMetricExporter_ClientProxy.assertCountPointsAtLeast(Unknown Source)