Rollup merge of #74376 - lcnr:type-dependent-path-cleanup, r=eddyb
Rollup merge of #74376 - lcnr:type-dependent-path-cleanup, r=eddyb

test caching opt_const_param_of on disc

Followup to #74113, implements parts of #74360

Tried caching `opt_const_param_of` on disk and adding an early exit if `tcx.dep_kind(def_id) != DefKind::AnonConst`.

Ended up causing a perf regression instead, so we just remove the FIXME and a short note to `opt_const_param_of`.

r? @eddyb

graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust