ci-operator/step-registry/gather/aws-console: Exclude empty-string "i…

…nstance IDs"

Like we did for GCP in 7e1a515 (ci-operator/step-registry/gather:
Exclude empty-string "instance IDs", 2020-12-19, openshift#14467).  In this
case, the empty-string example was [1]:

  Gathering console logs for
  /bin/bash: line 41: /logs/artifacts/: Is a directory

[1]: https://prow.ci.openshift.org/view/gs/origin-ci-test/pr-logs/pull/openshift_release/19836/rehearse-19836-pull-ci-openshift-origin-release-4.9-e2e-aws-disruptive

ci-operator/step-registry/gather/aws-console/gather-aws-console-commands.sh

@@ -34,7 +34,7 @@ fi
 aws --version
 
 REGION="$(jq -r .aws.region "${SHARED_DIR}/metadata.json")"
-cat "${TMPDIR}/node-provider-IDs.txt" | sort | uniq | while read -r INSTANCE_ID
+cat "${TMPDIR}/node-provider-IDs.txt" | sort | grep . | uniq | while read -r INSTANCE_ID
 do
 	echo "Gathering console logs for ${INSTANCE_ID}"
 	PYTHONIOENCODING=UTF-8:backslashreplace aws --region "${REGION}" ec2 get-console-output --instance-id "${INSTANCE_ID}" --output text > "${ARTIFACT_DIR}/${INSTANCE_ID}" &