Avoid memory leak when thread is reused (#1136)

This leak can happen if multiple copies of `smallrye-config` are loaded by different class loaders, like in Quarkus dev mode.

implementation/src/main/java/io/smallrye/config/SmallRyeConfigSourceInterceptorContext.java

@@ -32,7 +32,10 @@ public ConfigValue restart(final String name) {
         try {
             return config.interceptorChain().proceed(name);
         } finally {
-            rc.decrement();
+            if (rc.decrement()) {
+                // avoid leaking if the thread is cached
+                rcHolder.remove();
+            }
         }
     }
 
@@ -52,8 +55,8 @@ void increment() {
             count = old + 1;
         }
 
-        void decrement() {
-            count--;
+        boolean decrement() {
+            return --count == 0;
         }
     }
 }