resolve: Cleanup collection of resolved imports

[petrochenkov]

Addresses #159440 (comment).

[rustbot]

r? @davidtwco

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[petrochenkov]

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: fcdf694 (fcdf6945e519d821543528cad20686274b86f984)
Base parent: 79a4b00 (79a4b003dd31ab70729f19215aa13d1e68d86fb6)

[rust-timer]

Finished benchmarking commit (fcdf694): comparison URL.

Overall result: ❌ regressions - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.5%	[0.1%, 0.6%]	7
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 0.4%, secondary -3.7%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	1.5%	[1.5%, 1.5%]	1
Regressions ❌ (secondary)	5.4%	[5.4%, 5.4%]	1
Improvements ✅ (primary)	-0.6%	[-0.6%, -0.6%]	1
Improvements ✅ (secondary)	-6.0%	[-8.7%, -3.0%]	4
All ❌✅ (primary)	0.4%	[-0.6%, 1.5%]	2

Cycles

Results (primary 4.1%, secondary 5.6%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	4.1%	[2.5%, 5.0%]	3
Regressions ❌ (secondary)	5.6%	[4.7%, 6.5%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	4.1%	[2.5%, 5.0%]	3

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 489.717s -> 484.643s (-1.04%)
Artifact size: 388.55 MiB -> 387.84 MiB (-0.18%)