server: remove user-project mappings when delete a project - #14150

Description

This PR fixes #12601

When an account is added to a project with a project role (e.g. via addUserToProject), the resulting project_account row has a non-null user_id. Project cleanup (deleteProject ... cleanup=true) unassigns every account from the project via ProjectAccountDaoImpl#findByProjectIdUserId(projectId, accountId, null), expecting a null userId to mean "match this account regardless of which user_id the row has".

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)
• Build/CI
• Test (unit or integration test code)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

• Major
• Minor

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

Screenshots (if appropriate):

How Has This Been Tested?

Verified on a live 2-node management server deployment:

• Built and deployed the patched jar to both management nodes.
• Reproduced the original issue with the pre-fix code: created an account, created a project, added the account's user to the project with addUserToProject roletype=Admin (producing a project_account row with a non-null user_id), deleted the project with cleanup=true (reported success), then attempted deleteAccount — reproduced the exact errorcode 431 failure from Unable to delete account if the project is removed #12601.
• Repeated the same steps against the fixed jar: deleteProject cleanup=true followed by deleteAccount both succeeded, and the account no longer appeared in listAccounts.
• Confirmed both management nodes ended up running the identical fixed build.

How did you try to break this feature and the system with this change?