Rename `p2p.seeds` parameter to `p2p.bootstrappers`

[tzdybal]

We should consider whether p2p.seeds is the appropriate name for the flag. In Tendermint terminology seeds exist to inform nodes to other peers, not to share headers and such.

Originally posted by @jbowen93 in https://github.com/celestiaorg/optimint/issues/378#issuecomment-1112225054