Remove invalid command `kubectl autoscale deploy activator` in e2e-common.sh (#5799)
Remove invalid command `kubectl autoscale deploy activator` in e2e-common.sh (#5799)

* Remove invalid command `kubectl autoscale deploy activator` in e2e-common.sh

The HAP for actvator is already used by default after
https://github.com/knative/serving/commit/ae08d37e2f0073a248724cea44ef0fbb69bd0bb3.

Remaining the command, which is actually failing due to `already
exists` error, is confusable, so this patch removes it.

* Update minReplicas to 2 for activator pods

knative/serving,knative/serving