Allow Admin DeleteWorkflowExecution Delete by namespace ID

[yux0]

Is your feature request related to a problem? Please describe.
Admin DeleteWorkflowExecution currently takes in namespace. After a namespace is deleted, we don't have a way to delete data if there is leftover data.

Describe the solution you'd like
Admin DeleteWorkflowExecution takes in namespace ID to delete workflow data

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.