Fix metaspace leak through unreleased config on devmode restart

Some config was lazily created and bound to the dev class loader
through the configsForClassLoader map
io.smallrye.config.SmallRyeConfigProviderResolver#getConfig(java.lang.ClassLoader),
and the corresponding map entry was never cleared,
resulting in the corresponding classloader never being garbage
collected.

core/deployment/src/main/java/io/quarkus/deployment/dev/IsolatedDevModeMain.java

@@ -52,6 +52,7 @@
 import io.quarkus.runtime.ApplicationLifecycleManager;
 import io.quarkus.runtime.configuration.QuarkusConfigFactory;
 import io.quarkus.runtime.logging.LoggingSetupRecorder;
+import io.smallrye.config.SmallRyeConfigProviderResolver;
 
 public class IsolatedDevModeMain implements BiConsumer<CuratedApplication, Map<String, Object>>, Closeable {
 
@@ -291,19 +292,36 @@ public void stop() {
                 Thread.currentThread().setContextClassLoader(old);
             }
         }
-        QuarkusConfigFactory.setConfig(null);
 
+        // There may be multiple SmallryeConfigProviderResolver
+        // instances in multiple classloaders, and each of those may have registered config.
+        // Ideally we'd avoid getting in this situation,
+        // but due to config being lazily created in ConfigProviderResolver#getConfig,
+        // this is challenging.
+        // To avoid any leak, we try to clean up config in all relevant classloaders.
+        releaseConfig(Thread.currentThread().getContextClassLoader());
+        releaseConfig(getClass().getClassLoader());
+    }
+
+    private void releaseConfig(ClassLoader contextClassLoader) {
         ClassLoader old = Thread.currentThread().getContextClassLoader();
-        Thread.currentThread().setContextClassLoader(getClass().getClassLoader());
+        Thread.currentThread().setContextClassLoader(contextClassLoader);
         try {
+            QuarkusConfigFactory.setConfig(null);
             final ConfigProviderResolver cpr = ConfigProviderResolver.instance();
+            if (runner != null) {
+                // Clean up all references to the runner class loader,
+                // which may be using implicit config
+                // lazily created by ConfigProviderResolver#getConfig
+                ((SmallRyeConfigProviderResolver) cpr).releaseConfig(runner.getClassLoader());
+            }
+            // Clean up all references to classloaders using the explicitly registered config
             cpr.releaseConfig(cpr.getConfig());
         } catch (Throwable ignored) {
             // just means no config was installed, which is fine
         } finally {
             Thread.currentThread().setContextClassLoader(old);
         }
-        runner = null;
     }
 
     public void close() {