Revert custom IAM policy and role for nmfs-openscapes

[agoose77]

See for https://2i2c.freshdesk.com/a/tickets/3739 context.

For this workshop, we facilitated access of a particular bucket from Earthmover using IAM roles. We need to revert that imperative change after the workshop.

I've chosen some arbitrary dates after the workshop to do this.

Definition of Done

• IAM role (search earthmover) is deleted
• IAM policy (search earthmover) is deleted
• Consider refining an issue to support this properly in future