Don't initialize DeclarativeConfiguration in incubator available test (#7227)

Author: laurit

sdk-extensions/autoconfigure/src/main/java/io/opentelemetry/sdk/autoconfigure/AutoConfiguredOpenTelemetrySdkBuilder.java

@@ -64,7 +64,10 @@ public final class AutoConfiguredOpenTelemetrySdkBuilder implements AutoConfigur
   static {
     boolean incubatorAvailable = false;
     try {
-      Class.forName("io.opentelemetry.sdk.extension.incubator.fileconfig.DeclarativeConfiguration");
+      Class.forName(
+          "io.opentelemetry.sdk.extension.incubator.fileconfig.DeclarativeConfiguration",
+          false,
+          AutoConfiguredOpenTelemetrySdkBuilder.class.getClassLoader());
       incubatorAvailable = true;
     } catch (ClassNotFoundException e) {
       // Not available