[2.8.patch1] Port drone build tasks to gh workflows + actions

[richard-cox]

Occurred changes and/or fixed issues

• This is the backport of [2.8] Port drone build tasks to gh workflows + actions #11018
• It also includes the change
  • to split e2e build into a separate job (this will reduce runner load) Reduce the amount of time we spend running gh workflows #10691
  • remove stale docker files / references Remove two unused / maintained docker files and associated references #9763

Examples

• building from branch (with uploaded bits) - https://github.com/rancher/dashboard/actions/runs/9159052158
• building from tag (with uploaded bit) - https://github.com/rancher/dashboard/actions/runs/9160038772

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
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• 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

[nwmac]

Check the 2.8 tag

[richard-cox]

Note - Given #11093 (merge of release-2.8 to patch branch) the core changes have already been ported across