Rollup merge of #86096 - FabianWolff:ec-E0316, r=GuillaumeGomez

Comment out unused error codes and add description for E0316

I have added an extended description of `E0316` and commented out a bunch of unused error codes to make clear the fact that they are no longer in use. You can check for yourself with
```shell
for ec in                                                \
    E0314 E0315   E0473 E0474 E0475   E0479 E0480 E0481  \
    E0483 E0484 E0485 E0486 E0487 E0488 E0489
do
    if [ ! -z "`grep -r $ec compiler/* --exclude-dir=rustc_error_codes`" ]
    then
        echo $ec
        false
    fi
done
```
i.e. these error codes appear nowhere in the compiler code and thus cannot be emitted.

r? ```@GuillaumeGomez```

0 files changed, 0 insertions, 0 deletions