[lib] Remove isDefault field from RoleInfo in patchRoleInfoWithSpecialRole

Summary:
We update the existing patchRoleInfoWithSpecialRole utility used in the client migration to strip out the isDefault field from RoleInfo. It makes sense to include specialRole and exclude isDefault at the same time.

Depends on D11253

Test Plan:
Re-run migration on web and native

1. Make sure all RoleInfos have the specialRole field included (can be null, but must be included)
2. Make sure all RoleInfos have the isDefault field removed.
3. Look at keyserver logIn response payload and ensure that specialRole IS included and isDefault ISN'T included

Reviewers: ginsu, tomek, kamil, michal

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D11254