User roles upgrade is unsafe

We upgrade user roles before the corresponding upgrade of compat version.

This has multiple implications when the compat version upgrade fails:

1. It's possible to add an older node to the cluster. This node will not understand the updated user roles.

2. Until the compat version is properly updated, the users whose roles were updated may not be able to perform certain operations. This is because the set of roles that we check against depends on the compat version. So, for example, a security_admin that got upgraded will be locked out until compat version is upgraded.