[7.17](backport #30414) refactor pushDockerImages

[mergify]

This is an automatic backport of pull request #30414 done by Mergify.
Cherry-pick of 942b0e2 has failed:

On branch mergify/bp/7.17/pr-30414
Your branch is up to date with 'origin/7.17'.

You are currently cherry-picking commit 942b0e29a1.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	deleted:    .ci/scripts/docker-tag-push.sh

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   .ci/packaging.groovy

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

---

Mergify commands and options

More conditions and actions can be found in the documentation.

You can also trigger Mergify actions by commenting on this pull request:

• @Mergifyio refresh will re-evaluate the rules
• @Mergifyio rebase will rebase this PR on its base branch
• @Mergifyio update will merge the base branch into this PR
• @Mergifyio backport <destination> will backport this PR on <destination> branch

Additionally, on Mergify dashboard you can:

• look at your merge queues
• generate the Mergify configuration with the config editor.

Finally, you can contact us on https://mergify.com

[elasticmachine]

💚 Build Succeeded

the below badges are clickable and redirect to their specific view in the CI or DOCS

Expand to view the summary

Build stats

• Start Time: 2022-03-01T14:00:40.613+0000

• Duration: 118 min 38 sec

Test stats 🧪

Test	Results
Failed	0
Passed	55411
Skipped	5358
Total	60769

💚 Flaky test report

Tests succeeded.

🤖 GitHub comments

To re-run your PR in the CI, just comment with:

• /test : Re-trigger the build.

• /package : Generate the packages and run the E2E tests.

• /beats-tester : Run the installation tests with beats-tester.

• run elasticsearch-ci/docs : Re-trigger the docs validation. (use unformatted text in the comment!)

[v1v]

/package

[v1v]

Similar question @mdelapenya -> https://beats-ci.elastic.co/blue/organizations/jenkins/e2e-tests%2Fe2e-testing-mbp/detail/7.17/326/tests

but it's 7.17 rather than 8.1

[mdelapenya]

Similar question @mdelapenya -> https://beats-ci.elastic.co/blue/organizations/jenkins/e2e-tests%2Fe2e-testing-mbp/detail/7.17/326/tests

but it's 7.17 rather than 8.1

Those two seems not related to this PR, as we have detected certain flakiness in the k8s-autodiscover suite, while reading response from kubectl. Feel free to move forward with this PR