Remove "number of peers broadcasted to" info from TX events

[jsdw]

As of the v1 chainhead spec for transactionWatch_v1_submitAndWatch:

• The broadcasted event is no longer expected to be returned.

  smoldot/lib/src/json_rpc/methods.rs

  Line 831 in 423c8bb

  Broadcasted {

• broadcasted is no longer expected to be returned in the dropped event

  smoldot/lib/src/json_rpc/methods.rs

  Line 851 in 423c8bb

  broadcasted: bool,

Just something I noticed while in the area :)