[ty] Remove unused variants from various Known* enums (#18015)

## Summary

`KnownClass::Range`, `KnownInstanceType::Any` and `ClassBase::any()` are
no longer used or useful: all our tests pass with them removed.
`KnownModule::Abc` _is_ now used outside of tests, however, so I removed
the `#[allow(dead_code)]` branch above that variant.

## Test Plan

`cargo test -p ty_python_semantic`

crates/ty_python_semantic/src/module_resolver/module.rs

@@ -114,8 +114,7 @@ pub enum KnownModule {
     TypingExtensions,
     Typing,
     Sys,
-    #[allow(dead_code)]
-    Abc, // currently only used in tests
+    Abc,
     Dataclasses,
     Collections,
     Inspect,