Improve type safety in Micrometer HTTP server metrics

```
- Refactor context local data handling across Micrometer integration to improve type safety with generics.
- Simplify and clean up code by removing unnecessary type casts in `ContextLocalTag`.
```

Author: gastaldi

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/HttpServerMetricsTagsContributor.java

@@ -31,6 +31,6 @@ interface Context {
          * work when {@link HttpServerMetricsTagsContributor#contribute(Context)} is called as the HTTP request has
          * already gone away.
          */
-        Object requestContextLocalData(Object key);
+        <T> T requestContextLocalData(Object key);
     }
 }

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/binder/vertx/VertxHttpServerMetrics.java

@@ -271,7 +271,7 @@ public void disconnected(LongTaskTimer.Sample websocketMetric) {
     private record DefaultContext(HttpServerRequest request,
             HttpResponse response) implements HttpServerMetricsTagsContributor.Context {
         @Override
-        public Object requestContextLocalData(Object key) {
+        public <T> T requestContextLocalData(Object key) {
             return ((HttpServerRequestInternal) request).context().getLocal(key);
         }
     }

integration-tests/micrometer-prometheus/src/main/java/io/quarkus/ContextLocalTag.java

@@ -10,7 +10,7 @@ public class ContextLocalTag implements HttpServerMetricsTagsContributor {
 
     @Override
     public Tags contribute(Context context) {
-        String contextLocalData = (String) context.requestContextLocalData("context-local");
+        String contextLocalData = context.requestContextLocalData("context-local");
         return Tags.of("dummy", contextLocalData != null ? contextLocalData : "value");
     }
 }