Remove the tidy exceptions of custom-named tests module in std

[tesuji]

In #75979 (comment), Petrochenkov suggests
to merge src/thread/local/dynamic_tests.rs to src/thread/local/tests.rs. Note that dynamic_tests mod is gated
any platform cfgs but tests mod is. I'm not sure what would need to be done but one should wait until #75979
merged to start to work on this issue.

@rustbot modify labels:-S-blocked