Remove "AdministratorAccess" policy from "organization-formation-build-service-role" role

[k-paulius]

I am proposing removal of AdministratorAccess policy from organization-formation-build-service-role role.

I don't think this is a breaking change, because v0.9.15 of ofn implemented a change where it assumes OrganizationFormationBuildAccessRole to perform tasks in all accounts instead of using organization-formation-build-service-role to perform tasks in the local account and OrganizationFormationBuildAccessRole for tasks in non-local accounts (as described in 0.9.15-permission-change.md).

Because OrganizationFormationBuildAccessRole has AdministratorAccess policy attached to it and is used to execute all the tasks, organization-formation-build-service-role role no longer needs AdministratorAccess policy attached to it.

Inline policy organization-formation-build-service-role-policy that is currently attached to the organization-formation-build-service-role should have all permissions necessary for successful CodeBuild runs.