Deprecate the SoLarnet bootstrappers

[mburns]

fixes https://github.com/protocol/bifrost-infra/issues/680 , connected to ipfs/kubo#6797

The IPFS Infra team is retiring the "SoLarnet" boxen, those machines tarting with QmSoL... peerids, that are used to join (bootstrap) into the IPFS network. They are being replaced by 4 shiny, new bootstrap.libp2p.io machines, that we have precomputed and put in the default bootstrap list years ago (thanks, ghosts of infra past!)

Going forward, these addresses should be relied on:

/dnsaddr/bootstrap.libp2p.io/ipfs/QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN
/dnsaddr/bootstrap.libp2p.io/ipfs/QmQCU2EcMqAqQPR2i9bChDtGNJchTbq5TbXJJ16u19uLTa
/dnsaddr/bootstrap.libp2p.io/ipfs/QmbLHAnMoJPWSCR5Zhtx6BHJX9KiKNN6tpvbUcqanj75Nb
/dnsaddr/bootstrap.libp2p.io/ipfs/QmcZf59bWwK5XFi76CZX8cbJ4BhTzzA3gU1ZjYZcYW3dwt

We hard code these QmSoL addresses in a lot of places. I took a swipe at updating some of them:

• Add the 4 new libp2p bootstrappers js-ipfs#2581
• remove SoL-arnet boxen libp2p/js-libp2p-bootstrap#98
• retire SoL-arnet boxen libp2p/js-libp2p#554
• chore: remove solarnet boxen js-datastore-level#27
• remove SoLarnet boxen ipfs-inactive/js-ipfs-unixfs-importer#53

TODO

• talk with lead devs, make sure the change is understood.
• write up an announcement The IPFS bootstrap nodes seem to use 1024 bits RSA keys #378 (comment)
• doc updates CC @jessicaschilling (?)

[Stebalien]

Stop.

We can't do this unless we get rid of the recursive dnsaddr resolution. At the moment, reaching those new nodes depends on recursively resolving dns addrs and we only added support for that in go-ipfs 0.4.23.

I'm also not sure what the state of js-ipfs/js-libp2p is.

[olizilla]

We're not going to turn any solarnet boxen off. We'll let 0.5 get out the door, then we'll remove the solarnet entries from the defaults, then wait a good few releases before turning them off.

[mburns]

it has been a good few releases.

The SoLarnet boxen were quietly retired last week due to their legacy key size (https://github.com/protocol/bifrost-infra/issues/1118). Thanks to @gmas @aschmahmann @marten-seemann & @jacobheun for coordinating this.