fix: make EntityMetadataValidator comply with entitySkipConstructor

[francescosalvi]

Fixes #8444

Description of change

See related issue #8444

Pull-Request Checklist

• Code is up-to-date with the master branch
• npm run lint passes with this change
• npm run test passes with this change
• This pull request links relevant issues as Fixes #0000
• There are new or updated unit tests validating the change
• Documentation has been updated to reflect this change (N/A)
• The new commits follow conventions explained in [CONTRIBUTING.md]

[pleerock]

Can we have this change test-covered, so we can make sure in the future this won't break? Thank you

[francescosalvi]

@pleerock ok, I'll try

[francescosalvi]

@pleerock test added: I basically asserted that with and without the connection option, and the given entity, the connection should/should not be established (initially I defined an additional entity with the destructuring assignment in the constructor, but the error message seemed to differ among different Node versions, so I removed and only kept the current test entity where I assert that the passed parameter is not undefined)

[pleerock]

I'm thinking to revert entitySkipConstructor feature at all because of the following issue: #8267

[pleerock]

okay, let's merge it for now