Set scalability test timeout to 6h

As we want to test more clusters in scalability, the default 3h is not
enough. For now let's set it to 6h, but the timeout could be extended
even further in the future.

Signed-off-by: Huy Mai <[email protected]>

Author: Huy Mai

jenkins/jobs/capm3-e2e-tests.pipeline

@@ -27,7 +27,7 @@ script {
   } else if ( "${GINKGO_FOCUS}" == 'k8s-upgrade' ) {
     agent_label = "metal3ci-8c24gb-${IMAGE_OS}"
     TIMEOUT=14400 // 4h
-  } else if ( "${env.EPHEMERAL_TEST}" == 'true' ) {
+  } else if ( "${env.EPHEMERAL_TEST}" == 'true' || "${GINKGO_FOCUS}" == "scalability" ) {
     TIMEOUT=21600 // 6h
     agent_label = "metal3ci-8c32gb-${IMAGE_OS}"
   } else {