Rollup merge of #137800 - BoxyUwU:param_env_docs, r=compiler-errors

Remove `ParamEnv::without_caller_bounds`

This doesn't really do anything that `ParamEnv::empty` doesn't do nowadays as `ParamEnv` *only* stores caller bounds since other information has been moved out into `TypingMode`

r? ```@compiler-errors``` ```@lcnr```

Author: matthiaskrgr