IONOS(ci): forward the source ref name to the remote trigger (HDNEXT-1373)

[printminion-co]

Adds two --form variables to the remote trigger so the downstream release report can name the RC or branch a build came from, and link back to it:

• GITHUB_REF_NAME — github.ref_name verbatim (e.g. rc/web-v31-1). Already used in this step to derive BUILD_TYPE, and in the Artifactory path; it was simply not forwarded.
• GITHUB_REPOSITORY — saves the downstream from string-parsing SOURCE_BUILD_URL to build commit/branch/compare links.

BUILD_TYPE alone only says which lane a build came from (rc), losing the specific RC name (web-v31-1).

Notes

• Nothing is required of the consumer: both variables are optional the whole way down. The helm pipeline renders a valid, slightly thinner card when they are absent, so this can merge before or after the GitLab-side changes.
• Deliberately not added to the "Validate required variables" step — they are optional by design and must never fail a build.
• Same change on the other two lanes: …-v32 and …-v33 (v32/v33 are byte-identical here; v31 differs in indentation and comment table, hence separate PRs).

Downstream: hidrivenext-image MR !253, helm MR !293.

HDNEXT-1373