Add fast-path when computing the default visibility

[Urgau]

This PR adds (or more correctly re-adds the) fast-path when computing the default visibility, by taking advantage of the fact that the "interposable" requested visibility always return the "default" codegen visibility.

Should address the small regression observed in #131111 (comment).

r? @lqd

[lqd]

As cachegrind showed the small regressions in #130005 to be purely in the query system, I'm fully confident that the new unconditional query call to the expensive query was the source.

So, r=me with green perf and/or a cachegrind comparison between this and #130005 (or its parent commit). I expect the "PROGRAM TOTALS" line on a cg report for this PR to be the same as before the change was made.

[Urgau]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

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

[bors]

⌛ Trying commit 67b85e2 with merge 701880a...

[bors]

☀️ Try build successful - checks-actions
Build commit: 701880a (701880a6fab37ed2f0c178997183a43fe182dac0)

[rust-timer]

Queued 701880a with parent f6648f2, future comparison URL.
There are currently 0 preceding artifacts in the queue.
It will probably take at least ~1.2 hours until the benchmark run finishes.