fix: Trim the name of the image when building the job

autograde-service/src/main/java/ch/epfl/autograde/service/KubernetesJobService.java

@@ -242,7 +242,7 @@ public final class KubernetesJobService {
     private Container prepare_grading_container(Volume volume, Environment env, CreateSubmissionRequest request) {
         return new ContainerBuilder()
                 .withName("grader")
-                .withImage(env.image())
+                .withImage(env.image().trim())
                 .withImagePullPolicy(jobImageConfig.pullPolicy().toString())
                 .withVolumeMounts(new VolumeMountBuilder()
                         .withName(volume.getName())