Fix bugs discovered during customer migration

REMOVE IF ALREADY PART OF ISSUE DESCRIPTION

Overview

There are bugs when running user migrations, mainly:

• checking whether blocked users should be crated or not - user accounts are always created, regardless of the state and keep_inactive_users config value
• is username a group namespace lookup - an error (message) response returns on group search resulting in Exception

'str' object has no attribute 'get’

Tasks

• Fix bug in handle_user_creation function
• Fix bug is_username_group_name function
• Fix bug in __walk_tags of registries.py for ERROR

Project devops/ci (ID: 17) registries <generator object GitLabApi.list_all at 0x7fee15a45dd0> 'builtin_function_or_method' object is not subscriptable

• Update docs if needed (workflow, runbooks, README, migration metrics, etc.)

Acceptance Criteria

• Existing UTs pass locally