Make a custom ContextManagerProvider with a single manager

Because Quarkus doesn't care about one-per CL and Franz said this is a
bottleneck for some reason

extensions/smallrye-context-propagation/runtime/src/main/java/io/quarkus/smallrye/context/runtime/QuarkusContextManagerProvider.java

@@ -0,0 +1,42 @@
+package io.quarkus.smallrye.context.runtime;
+
+import org.eclipse.microprofile.context.spi.ContextManager;
+
+import io.smallrye.context.SmallRyeContextManager;
+import io.smallrye.context.SmallRyeContextManagerProvider;
+
+/**
+ * Quarkus doesn't need one manager per CL, we only have the one
+ */
+public class QuarkusContextManagerProvider extends SmallRyeContextManagerProvider {
+
+    private SmallRyeContextManager contextManager;
+
+    @Override
+    public SmallRyeContextManager getContextManager(ClassLoader classLoader) {
+        return contextManager;
+    }
+
+    @Override
+    public SmallRyeContextManager getContextManager() {
+        return contextManager;
+    }
+
+    @Override
+    public ContextManager findContextManager(ClassLoader classLoader) {
+        return contextManager;
+    }
+
+    @Override
+    public void registerContextManager(ContextManager manager, ClassLoader classLoader) {
+        if (manager instanceof SmallRyeContextManager == false) {
+            throw new IllegalArgumentException("Only instances of SmallRyeContextManager are supported: " + manager);
+        }
+        contextManager = (SmallRyeContextManager) manager;
+    }
+
+    @Override
+    public void releaseContextManager(ContextManager manager) {
+        contextManager = null;
+    }
+}

extensions/smallrye-context-propagation/runtime/src/main/java/io/quarkus/smallrye/context/runtime/SmallRyeContextPropagationRecorder.java

@@ -14,7 +14,6 @@
 import io.quarkus.runtime.ShutdownContext;
 import io.quarkus.runtime.annotations.Recorder;
 import io.smallrye.context.SmallRyeContextManager;
-import io.smallrye.context.SmallRyeContextManagerProvider;
 import io.smallrye.context.SmallRyeManagedExecutor;
 import io.smallrye.context.SmallRyeThreadContext;
 
@@ -31,7 +30,7 @@ public void configureStaticInit(List<ThreadContextProvider> discoveredProviders,
         // build the manager at static init time
         // in the live-reload mode, the provider instance may be already set in the previous start
         if (ContextManagerProvider.INSTANCE.get() == null) {
-            ContextManagerProvider contextManagerProvider = new SmallRyeContextManagerProvider();
+            ContextManagerProvider contextManagerProvider = new QuarkusContextManagerProvider();
             ContextManagerProvider.register(contextManagerProvider);
         }