Remove std::fmt::Display implementation for std::bstr::ByteStr/ByteString

[DanielEScherzer]

Part of #134915
r? @BurntSushi

[rust-log-analyzer]

The job x86_64-gnu-next-trait-solver-polonius failed! Check out the build log: (web) (plain enhanced) (plain)

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    |
help: the trait `fmt::Display` is not implemented for `ByteStr`
   --> library/core/src/bstr/mod.rs:40:1
    |
 40 | pub struct ByteStr(pub [u8]);
    | ^^^^^^^^^^^^^^^^^^

For more information about this error, try `rustc --explain E0277`.
[RUSTC-TIMING] core test:false 18.947
error: could not compile `core` (lib) due to 1 previous error

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[BurntSushi]

I would guess that we will want [u8]::display too, so keeping this functionality around is probably wise.

Note also that this is a suggestion on my part. Idk if there is consensus yet.