Optimize visible_parent_map to use LRC to prevent unnecessary cloning

[In-line]

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[rust-highfive]

r? @wesleywiser

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[In-line]

r? @Mark-Simulacrum

Please, kindly schedule a perf run, in accordinness with #87349 (comment)

[Mark-Simulacrum]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

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

[bors]

⌛ Trying commit 139e946 with merge cd95aa6bd6b91571b700b7d3f390c47d105237c8...

[bors]

☀️ Try build successful - checks-actions
Build commit: cd95aa6bd6b91571b700b7d3f390c47d105237c8 (cd95aa6bd6b91571b700b7d3f390c47d105237c8)

[rust-timer]

Queued cd95aa6bd6b91571b700b7d3f390c47d105237c8 with parent 8ad3c1d, future comparison URL.

[rust-timer]

Finished benchmarking commit (cd95aa6bd6b91571b700b7d3f390c47d105237c8): comparison url.

Summary: This benchmark run did not return any relevant changes.

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR led to changes in compiler perf.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf -perf-regression

[Mark-Simulacrum]

Closing in favor of #92169.