security/p2p: prevent peers who errored being added to the peer_set (backport #9500) (#9516)

* security/p2p: prevent peers who errored being added to the peer_set (#9500)

* Mark failed removal of peer to address security bug

Co-authored-by: Callum Waters <cmwaters19@gmail.com>
(cherry picked from commit c0bdb2423a)

* Changelong entry and added missing functions for implementations of Peer

Co-authored-by: Jasmina Malicevic <jasmina.dustinac@gmail.com>

blockchain/v2/reactor_test.go

@@ -59,6 +59,9 @@ func (mp mockPeer) TrySend(byte, []byte) bool { return true }
 func (mp mockPeer) Set(string, interface{}) {}
 func (mp mockPeer) Get(string) interface{}  { return struct{}{} }
 
+func (mp mockPeer) SetRemovalFailed()      {}
+func (mp mockPeer) GetRemovalFailed() bool { return false }
+
 type mockBlockStore struct {
 	blocks map[int64]*types.Block
 }