TASK: Remove obsolete OUTDATED_CONFLICT state leftovers

[mhsdesign]

Resolves: #5101

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MUST BE CAREFULLY REVIEWED... please dont trust my proposal :D

with https://github.com/neos/neos-development-collection/pull/4965 we never create rebase was failed events anymore and the logic to query OUTDATED_CONFLICT workspaces was removed. To have a consistent and understandable codebase without dead artefacts i removed the OUTDATED_CONFLICT flag and for the legacy event (in case of a replay) OUTDATED will be written to the database as otherwise the workspace will probably disappear and not be to recover

Checklist

• [ ] Code follows the PSR-2 coding style
• [ ] Tests have been created, run and adjusted as needed
• [ ] The PR is created against the lowest maintained branch
• [ ] Reviewer - PR Title is brief but complete and starts with FEATURE|TASK|BUGFIX
• [ ] Reviewer - The first section explains the change briefly for change-logs
• [ ] Reviewer - Breaking Changes are marked with !!! and have upgrade-instructions

[pKallert]

Since we remove the OUTDATED_CONFLICT, perhaps the test scenario text here should be adjusted? https://github.com/neos/neos-development-collection/blob/10e3259a02da4bc7b91d615d79de7fa9f11e9263/Neos.ContentRepository.BehavioralTests/Tests/Behavior/Features/W6-WorkspaceRebasing/03-RebasingWithConflictingChanges.feature#L49