Fix issue 22139 - Compiler special cases object.dup when compiling with -preview=dip1000

[dkorpel]

Let's see if we can remove it now #12890 is merged

[dlang-bot]

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	22139	normal	Compiler special cases object.dup when compiling with -preview=dip1000

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + dmd#13571"