Drop a few unused diagnostic codes

Avoids warnings during bootstrap, similar to:

  src/librustc/lib.rs:149:1: 149:39 warning: diagnostic code E0099 never used
  src/librustc/lib.rs:149 __build_diagnostic_array!(DIAGNOSTICS)

All of these codes stopped being used in this commit:
688ddf7 ("typeck/kind -- stop using old trait framework.")

See also similar fix: https://github.com/rust-lang/rust/issues/16449