Merge branch '439300-remove-legacy-value-streams-dashboard-haml-file' into 'master'

Remove legacy value streams dashboard haml file

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/166865



Merged-by: Felipe Cardozo <fcardozo@gitlab.com>
Approved-by: Alex Pennells <apennells@gitlab.com>
Approved-by: Felipe Cardozo <fcardozo@gitlab.com>
Co-authored-by: Ezekiel Kigbo <ekigbo@gitlab.com>