chore(e2e): use a fixed digit of SHORT_SHA for image name

[josephca]

Description

To have consistent image names with SHORT_SHA as a suffix, use git rev-parse --short=8. Otherwise, we would get inconsistent number of digits from the command.

Which issue(s) does this PR fix

• Fixes RHIDP-4775

PR acceptance criteria

Please make sure that the following steps are complete:

• GitHub Actions are completed and successful
• Unit Tests are updated and passing
• E2E Tests are updated and passing
• Documentation is updated if necessary (requirement for new features)
• Add a screenshot if the change is UX/UI related

How to test changes / Special notes to the reviewer

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[github-actions]

The image is available at: quay.io/janus-idp/backstage-showcase:pr-1873!

[PatAKnight]

/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: gustavolira, PatAKnight

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[kim-tsao]

/cherry-pick release-1.3

[openshift-cherrypick-robot]

@kim-tsao: new pull request created: #1888

In response to this:

/cherry-pick release-1.3

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[kim-tsao]

/cherry-pick 1.2.x

[openshift-cherrypick-robot]

@kim-tsao: new pull request created: #1889

In response to this:

/cherry-pick 1.2.x

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.