chore: remove deprecated packages keyword from log4j configs

The original packages keyword in our real config file was removed quite a while ago

Author: FSchumacher

bin/testfiles/log4j2-batch.xml

@@ -15,7 +15,7 @@
    See the License for the specific language governing permissions and
    limitations under the License.
 -->
-<Configuration status="WARN" packages="org.apache.jmeter.gui.logging">
+<Configuration status="WARN">
 
   <Appenders>
 

src/core/src/testFixtures/resources/log4j2.xml

@@ -16,7 +16,7 @@
   ~ limitations under the License.
   -->
 
-<Configuration status="WARN" packages="org.apache.jmeter.gui.logging">
+<Configuration status="WARN">
 
   <Appenders>