fix(db-postgres): add ON DELETE CASCADE to foreign key constraint of select hasMany relationship

[ikenox]

Description

This PR fixes #6485.

• I have read and understand the CONTRIBUTING.md document in this repository.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have added tests that prove my fix is effective or that my feature works
• Existing test suite passes locally with my changes

[ikenox]

Hi @DanRibbens ,
This bug seems critical and easy to fix. Cloud you review this PR?
I know payload team is working hard for v3, thanks.

[DanRibbens]

Thanks for the PR!

[DanRibbens]

Thank you for the nudge on this @ikenox. Once the tests pass we'll get merged.

[ikenox]

@DanRibbens
Thank you for your immediate response!

The failing test says the following.

  MongoServerError: WriteConflict error: this operation conflicted with another operation. Please retry your operation or multi-document transaction.

        at Connection.onMessage (/home/runner/work/payload/payload/node_modules/.pnpm/mongodb@4.17.1/node_modules/mongodb/src/cmap/connection.ts:449:20)
        at MessageStream.<anonymous> (/home/runner/work/payload/payload/node_modules/.pnpm/mongodb@4.17.1/node_modules/mongodb/src/cmap/connection.ts:241:56)
        at processIncomingData (/home/runner/work/payload/payload/node_modules/.pnpm/mongodb@4.17.1/node_modules/mongodb/src/cmap/message_stream.ts:188:12)
        at MessageStream._write (/home/runner/work/payload/payload/node_modules/.pnpm/mongodb@4.17.1/node_modules/mongodb/src/cmap/message_stream.ts:69:5)

This mongo-db error seems not to be related to the change of this pull request.
The same error often occurs on main branch (e.g. this commit), so this maybe a flaky test.

[DanRibbens]

This has already been done in beta, no additional PR needed.

Thanks for the contribution @ikenox!