fixup(infra.ci): correct the command for amd/arm agents

[smerle33]

related to jenkins-infra/helpdesk#3823

as per the error :

Error in provisioning; agent=KubernetesSlave name: jnlp-linux-arm64-5wgv9, template=PodTemplate{id='redacted', name='jnlp-linux-arm64', label='jnlp-linux-arm64', nodeSelector='kubernetes.io/arch=arm64', containers=[ContainerTemplate{name='jnlp', image='jenkinsciinfra/jenkins-agent-ubuntu-22.04:1.42.0', alwaysPullImage=true, workingDir='/home/jenkins/agent', **command='sleep', args='9999999'**, resourceRequestCpu='500m', resourceRequestMemory='512Mi', resourceRequestEphemeralStorage='', resourceLimitCpu='500m', resourceLimitMemory='512Mi', resourceLimitEphemeralStorage='', envVars=[KeyValueEnvVar [getValue()=/opt/java/openjdk/bin/java, getKey()=JENKINS_JAVA_BIN]], livenessProbe=ContainerLivenessProbe{execArgs='', timeoutSeconds=0, initialDelaySeconds=0, failureThreshold=0, periodSeconds=0, successThreshold=0}}]}

we need to correct the command to launch the agent jar