Avoid duplicate steps in snyk artifact scanning

[donoghuc]

Release notes

[rn:skip]

What does this PR do?

In the case where two release tracks point to the same version, we need to guard against duplicate step names. This is a rare occurance that is otherwise harmless. This commit guards against duplicate step names.

merging logstash-plugins/.ci#110 revealed this quirk.

[github-actions]

🤖 GitHub comments

Just comment with:

• run docs-build : Re-trigger the docs validation. (use unformatted text in the comment!)
• run exhaustive tests : Run the exhaustive tests Buildkite pipeline.

[mergify]

This pull request does not have a backport label. Could you fix it @donoghuc? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit.
• If no backport is necessary, please add the backport-skip label

[donoghuc]

Example pipeline https://buildkite.com/elastic/logstash-artifacts-snyk-report-ci/builds/22

[donoghuc]

Example pipeline is pushing the expected versions through to snyk ✅

[elasticmachine]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 80ad89d

Failed CI Steps

• 🥼 Integration Tests - FIPS mode / part 3-of-6
• 🥼 IT Persistent Queues / part 4-of-6