Update organization_users on member creation

What does this MR do and why?

Update organization_users on member creation

• needed to keep track of users that are part of an organization which is triggered by becoming a member.
• invite acceptance in follow-on MR: !140595 (merged)

See #419366 (closed) for more details

Database

upsert analysis - https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/25036/commands/79527

note: update since !140817 (merged) merged and rebased into this branch:

• before latest commit access_level is added to the query: https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/25138/commands/79841
• with latest commit back to original analysis as we skip duplicates: https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/25138/commands/79842

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #419366 (closed)