Rename Packets to PacketBatch (backport #21794) (#21805)

* Rename Packets to PacketBatch (#21794)

(cherry picked from commit 254ef3e7b6)

# Conflicts:
#	core/src/verified_vote_packets.rs

* resolve conflicts

Co-authored-by: Justin Starry <justin@solana.com>

perf/benches/recycler.rs

@@ -3,7 +3,7 @@
 extern crate test;
 
 use {
-    solana_perf::{packet::PacketsRecycler, recycler::Recycler},
+    solana_perf::{packet::PacketBatchRecycler, recycler::Recycler},
     test::Bencher,
 };
 
@@ -11,7 +11,7 @@ use {
 fn bench_recycler(bencher: &mut Bencher) {
     solana_logger::setup();
 
-    let recycler: PacketsRecycler = Recycler::default();
+    let recycler: PacketBatchRecycler = Recycler::default();
 
     for _ in 0..1000 {
         let _packet = recycler.allocate("");