Auto-install helm in wait_for_charts_availability.sh if not present

What does this MR do?

Fixes the release_package CI job failure where helm command is not found.

The release_package job uses the distribution_ci_tools Docker image which does not include helm. The wait_for_charts_availability.sh script requires helm to check chart availability on charts.gitlab.io.

This MR reverts the runtime helm install approach. Instead, helm is being added directly to the distribution_ci_tools image in:

• gitlab-org/gitlab-omnibus-builder!469 (merged)

Once that MR is merged and a new image version is published, this job will work without any script changes.

Failed job: https://dev.gitlab.org/gitlab/charts/gitlab/-/jobs/35772796

Related issues

Author checklist

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Required

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• Merge Request Title and Description are up to date, accurate, and descriptive.
• MR targeting the appropriate branch.
• MR has a green pipeline.
• Documentation created/updated.
• Tests added/updated, and test plan for scenarios not covered by automated tests.
• Equivalent MR/issue for omnibus-gitlab opened.

Reviewers checklist

• MR has a green pipeline on https://gitlab.com/gitlab-org/charts/gitlab.
• Consider downstream impact to the Operator, as per evaluating impact from changes to GitLab chart.