ci: add Branch Helm E2E workflow gated on test:e2e-helm #9

Job	Run time
Resolve PR metadata	7s
build-supervisor / Resolve build plan	4s
build-gateway / Resolve build plan	2s
build-gateway / Rust gateway (amd64) / gateway (amd64)	3m 43s
build-supervisor / Rust sandbox (amd64) / sandbox (amd64)	2m 33s
build-supervisor / Build supervisor (amd64)	1m 12s
build-gateway / Build gateway (amd64)	1m 24s
build-supervisor / Merge ${{ inputs.component }} manifest	0s
Helm E2E (Rust smoke)	2m 40s
build-gateway / Merge ${{ inputs.component }} manifest	0s
	11m 45s

Provide feedback