Investigate if stamp logic in bootstrap could be consistently handled

[jieyouxu]

We were looking to revisit the tool_check_step! macro in check logic in #134950, but found that stamp logic was scattered. Different check steps (and probably other step kinds) might not have their stamp logic be consistently handled if only one stamp logic site is changed but not the others.

Change of stamp looks sus: the same stamps build in

rust/src/bootstrap/src/core/build_steps/clippy.rs

Line 312 in 41b5796

.join(format!(".{}-check.stamp", stringify!($name).to_lowercase()));

too, but now they desync. I think it's simpler to revert it in current pr (and optionally rework stamps in separate pr, so they can be produces somehow centralized).

Originally posted by @klensy in #134950 (comment)

Might be valuable to double-check how stamps are handled throughout bootstrap, and possibly unify the stamp handling logic so they don't risk diverging.

[Zalathar]

I suspect that some of these “stamps” are actually just an overcomplicated way to tell cargo which build directory to use, with the actual stamp itself never actually being read anywhere.

But I'm not yet confident enough to take action on that basis.

[Zalathar]

In particular, note that the stamp path is used to derive target_root_dir, so a stamp path is needed (and a stamp is written) regardless of whether the stamp is actually needed for anything.

rust/src/bootstrap/src/core/build_steps/compile.rs

Lines 2033 to 2034 in 41b5796

	// `target_root_dir` looks like $dir/$target/release
	let target_root_dir = stamp.parent().unwrap();