Rollup merge of #66678 - GuillaumeGomez:remove-useless-error-index-line, r=Dylan-DPC
Rollup merge of #66678 - GuillaumeGomez:remove-useless-error-index-line, r=Dylan-DPC

Remove useless line for error index generation

As you can see here: https://github.com/rust-lang/rust/blob/master/src/librustc_error_codes/error_codes.rs#L10, this replacement is now completely useless.

r? @Dylan-DPC

graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust