Make PushDownDereferenceThroughProject to not fire on non-identity source

[weiatwork]

Description

Fixes #15659

Additional context and related issues

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# Section
* Fix some things. ({issue}`issuenumber`)

[weiatwork]

@martint I understand that #15680 will fix the issue from the perspective of not producing problematic symbol mappings. But I think the fix of this PR is still needed, as a local fix and safeguard to the specific rule

[github-actions]

This pull request has gone a while without any activity. Tagging the Trino developer relations team: @bitsondatadev @colebow @mosabua

[bitsondatadev]

@weiatwork looks like #15659 was fixed by #15680. I am closing this for now. Feel free to reopen if there is another issue that is left unresolved. Thank you!

[weiatwork]

Hi Brian, thanks for the housekeeping. I understand that the original issue was fixed via a different PR. I was waiting on @martint to take a look if the change in this PR is still necessary, as a safeguard

[bitsondatadev]

Ah cool, I'll reach out to him.

[github-actions]

This pull request has gone a while without any activity. Tagging the Trino developer relations team: @bitsondatadev @colebow @mosabua

[mosabua]

@martint I think this can be closed now since you just merged a related PR. See links in the issue.

[github-actions]

This pull request has gone a while without any activity. Tagging the Trino developer relations team: @bitsondatadev @colebow @mosabua

[github-actions]

Closing this pull request, as it has been stale for six weeks. Feel free to re-open at any time.