fix: Delete not re-created tracked structs after fixpoint iteration

[MichaReiser]

This PR fixes a regression that I introduced with #969

#969 moves the tracked structs out from QueryRevisions::origin and instead tracks the "alive" tracked ids directly in IdentityMap. Completing the IdentityMap then returns to vecs:

1. The alive tracked struct ids and their identity
2. The not re-created tracked struct ids

Unlike before #969, the not re-created tracked struct ids are identified eagerly when completing the query. This isn't an issue for non-cyclic queries but it resulted in leaking if a cyclic query didn't create all tracked structs in the first iteration of the second revision.

This is fixed in this PR. I added a regression test and verified that the logs match the behavior before we merged #969.

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[codspeed-hq]

CodSpeed Performance Report

Merging #979 will improve performances by 5.17%

_{Comparing MichaReiser:diff-tracked-structs-cycle (8b7e3b9) with master (411f844)}

Summary

⚡ 2 improvements
✅ 10 untouched benchmarks

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	amortized[Input]	2.4 µs	2.3 µs	+5.17%
⚡	amortized[SupertypeInput]	3 µs	2.9 µs	+5.11%

[MichaReiser]

@carljm Could you take a look at this?

[carljm]

Sorry, not sure how I missed this. Looks good, thank you! Needs a clippy expect in the test.