fix(test): configure mockito as javaagent to suppress self-attach warning (kroxylicious#3579)

Add -javaagent arg for mockito-core to both maven-surefire-plugin and
maven-failsafe-plugin in the parent POM. This ensures Mockito is loaded
as a proper Java agent rather than self-attaching at runtime, which
eliminates the deprecation warning and prepares for future JDK versions
that will disallow dynamic agent loading.

Fixes kroxylicious#3576

Signed-off-by: Tanner Smith <griffonbyte@proton.me>
Co-authored-by: Sam Barker <sam@quadrocket.co.uk>

Author: griffonbyte

pom.xml

@@ -742,6 +742,9 @@
                             <io.netty.leakDetection.level>paranoid</io.netty.leakDetection.level>
                             <container.logs.dir>${project.build.directory}/container-logs/</container.logs.dir>
                         </systemPropertyVariables>
+                        <argLine>
+                            -javaagent:${settings.localRepository}/org/mockito/mockito-core/${mockito.version}/mockito-core-${mockito.version}.jar
+                        </argLine>
                         <runOrder>random</runOrder>
                     </configuration>
                     <executions>
@@ -800,6 +803,7 @@
                             <usePhrasedTestCaseMethodName>true</usePhrasedTestCaseMethodName>
                         </statelessTestsetReporter>
                         <argLine>
+                            -javaagent:${settings.localRepository}/org/mockito/mockito-core/${mockito.version}/mockito-core-${mockito.version}.jar
                             -Dio.netty.allocator.type=pooled
                             @{jacoco.argline}
                         </argLine>