Fix HelmOps DownstreamResources - move from spec.helm to spec

[torchiaf]

Summary

Fixes #15344

Occurred changes and/or fixed issues

The UI is saving the HelmOp's downstreamResources in the wrong field

Technical notes summary

• It fixes the downstreamResources field: HelmOp.spec.helm -> HelmOp.spec
• It adds tooltips based on the Fleet documentation - https://fleet.rancher.io/experimental-downstream-resources postponed to 2.14

Areas or cases that should be tested

• Fleet -> HelmOps -> Advanced step -> select ConfigMaps and Secrets

Areas which could experience regressions

Screenshot/Video

Screencast.from.2025-11-12.10-23-42.webm

Checklist

• The PR is linked to an issue and the linked issue has a Milestone, or no issue is needed
• The PR has a Milestone
• The PR template has been filled out
• The PR has been self reviewed
• The PR has a reviewer assigned
• The PR has automated tests or clear instructions for manual tests and the linked issue has appropriate QA labels, or tests are not needed
• The PR has reviewed with UX and tested in light and dark mode, or there are no UX changes
• The PR has been reviewed in terms of Accessibility
• The PR has considered, and if applicable tested with, the three Global Roles Admin, Standard User and User Base

[cnotv]

LGTM

[cnotv]

Pipeline needs to be fixed, but for a next quicker review LGTM ✅