Update id collision checks with missing checks from CMFPlone.

[thet]

Some of the checks in utils._check_for_collision or erronous. These checks were updated with the original checks from CMFPlone. The tests depend on a fully set-up site and remain in CMFPlone.

While working on plone/Products.CMFPlone#4282 the failing tests revealed an incomplete _check_for_collision method. Before PR 4282 the cmfplone tests were importing the _check_for_collision method from CMFPlone itself which was nowhere used anymore except in the tests, so the failure in plone.base.utils._check_for_collision did not surface.
This PR and the one in plone/Products.CMFPlone#4282 fixes that.

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• If needed, I added new tests for my changes.
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• I included a change log entry in my commits.

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[mister-roboto]

@thet thanks for creating this Pull Request and helping to improve Plone!

TL;DR: Finish pushing changes, pass all other checks, then paste a comment:

@jenkins-plone-org please run jobs

To ensure that these changes do not break other parts of Plone, the Plone test suite matrix needs to pass, but it takes 30-60 min. Other CI checks are usually much faster and the Plone Jenkins resources are limited, so when done pushing changes and all other checks pass either start all Jenkins PR jobs yourself, or simply add the comment above in this PR to start all the jobs automatically.

Happy hacking!