Pass organization_id when creating OAuth Applications

What does this MR do and why?

Backport of !9548 (merged) to 19-0-stable.

Adds DEFAULT_ORGANIZATION_ID = 1 and updates create_or_find_authorization to:

1. Pass organization_id: DEFAULT_ORGANIZATION_ID in the create! call for newly created OAuth applications.
2. Backfill organization_id via update_column for existing apps with a NULL organization_id found during gitlab-ctl reconfigure.

This fixes a PG::CheckViolation on the check_77eda6baaa constraint of the oauth_applications table enforced by the post-deploy migration add_not_null_constraint_to_oauth_applications_organization_id, which causes post_deploy_db_migrations to fail during 19.0 upgrades.

This is the critical backport for GitLab Dedicated instances upgrading from 18.11 → 19.0. See https://gitlab.com/gitlab-com/gl-infra/gitlab-dedicated/team/-/work_items/12901#note_3490075217 for the original report.

Note: This targets 19-0-stable which is outside the current maintenance policy. Release manager approval is required via #releases Slack.

MR acceptance checklist

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

• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The original MR has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).

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