HDDS-13069. Error stopping S3 Gateway admin webserver

[adoroszlai]

What changes were proposed in this pull request?

Workaround for the following exception, which happens when shutting down S3 Gateway:

ozone-s3g-1 | 2025-05-19 08:01:22,234 [shutdown-hook-0] ERROR http.HttpServer2: Error while stopping web app context for webapp s3g-web
ozone-s3g-1 | java.lang.IllegalStateException: Singleton not set for STATIC_INSTANCE => []
ozone-s3g-1 | 	at org.jboss.weld.bootstrap.api.helpers.RegistrySingletonProvider$RegistrySingleton.get(RegistrySingletonProvider.java:28)
...
ozone-s3g-1 | 	at org.eclipse.jetty.util.component.AbstractLifeCycle.stop(AbstractLifeCycle.java:94)
ozone-s3g-1 | 	at org.apache.hadoop.hdds.server.http.HttpServer2.stop(HttpServer2.java:1361)
ozone-s3g-1 | 	at org.apache.hadoop.hdds.server.http.BaseHttpServer.stop(BaseHttpServer.java:344)
ozone-s3g-1 | 	at org.apache.hadoop.ozone.s3.Gateway.stop(Gateway.java:112)

This change catches the exception to allow shutdown to complete.

https://issues.apache.org/jira/browse/HDDS-13069

How was this patch tested?

Verified that S3 Gateway shutdown continues after error is logged:

cd hadoop-ozone/dist/target/ozone-2.2.0-SNAPSHOT/compose/ozone
OZONE_DATANODES=3 ./run.sh -d
docker compose stop s3g
docker compose logs s3g

s3g-1  | 2026-02-17 10:10:26,855 [shutdown-hook-0] INFO s3.Gateway: Stopping Ozone S3 gateway
s3g-1  | 2026-02-17 10:10:26,866 [shutdown-hook-0] INFO handler.ContextHandler: Stopped o.e.j.w.WebAppContext@3006bfb{s3gateway,/,null,STOPPED}{jar:file:/opt/hadoop/share/ozone/lib/ozone-s3gateway-2.2.0-SNAPSHOT.jar!/webapps/s3gateway}
...
s3g-1  | 2026-02-17 10:10:26,873 [shutdown-hook-0] ERROR http.HttpServer2: Error while stopping web app context for webapp s3g-web
...
s3g-1  | 2026-02-17 10:10:26,876 [shutdown-hook-0] INFO handler.ContextHandler: Stopped o.e.j.w.WebAppContext@6339e604{s3g-web,/,null,STOPPED}{jar:file:/opt/hadoop/share/ozone/lib/ozone-s3gateway-2.2.0-SNAPSHOT.jar!/webapps/s3g-web}
s3g-1  | 2026-02-17 10:10:26,877 [JvmPauseMonitor0] INFO util.JvmPauseMonitor: JvmPauseMonitor-S3G: Stopped

CI:
https://github.com/adoroszlai/ozone/actions/runs/22091412549

[sarvekshayr]

Thanks @adoroszlai for the fix. Verified the changes and it looks good to me.