Remove several alumni from experts/map.toml

[workingjubilee]

This file is an attractive nuisance that inspires people to bother contributors who have decided their time with the project is done. Perhaps it should be simply deleted wholesale. That seems like a somewhat radical position, so I merely culled several names that haven't contributed to the compiler recently, or that I recognize as having actively decided to distance themselves. Or, in one case, an officially-over project.

[nnethercote]

There is another TOML file somewhere (I don't remember where) that defines who can review certain parts of the compiler. That seems like the more definitive guide for this kind of information, and less likely to get out of date given that it affects the review distribution.

[jackh726]

I agree that this is probably not a good place for this type of information, but given that it's here, any improvement is worth it.

Am going to go ahead and merge this, but we should consider removing it outright.

[spastorino]

Have commented about this in a similar PR that was done to the dev guide. I think we should remove this file probably cc @davidtwco @wesleywiser

[jyn514]

There is another TOML file somewhere (I don't remember where) that defines who can review certain parts of the compiler. That seems like the more definitive guide for this kind of information, and less likely to get out of date given that it affects the review distribution.

https://github.com/rust-lang/rust/blob/7be0546bd121c06b37cce9139af8b7c7e012cb25/triagebot.toml#L627-L804

[davidtwco]

Have commented about this in a similar PR that was done to the dev guide. I think we should remove this file probably cc @davidtwco @wesleywiser

I lean in this direction too - experts map has never been something we've been good at keeping up-to-date, so we should probably look at other approaches at solving this problem.

[spastorino]

Done in #698