Update 3.5 changelog to cover the PR of improving health check

[ahrtr]

Update 3.5 change log to cover the PR #13706

cc @serathius @ptabor @spzala

[codecov-commenter]

Codecov Report

Merging #13725 (b3a53af) into main (b5e224d) will decrease coverage by 0.28%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main   #13725      +/-   ##
==========================================
- Coverage   72.95%   72.67%   -0.29%     
==========================================
  Files         466      466              
  Lines       38201    38201              
==========================================
- Hits        27870    27761     -109     
- Misses       8535     8634      +99     
- Partials     1796     1806      +10     

Flag	Coverage Δ
all	72.67% <ø> (-0.29%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
server/etcdserver/api/rafthttp/peer_status.go	87.87% <0.00%> (-12.13%)	⬇️
server/proxy/grpcproxy/register.go	69.76% <0.00%> (-9.31%)	⬇️
server/etcdserver/api/rafthttp/peer.go	87.01% <0.00%> (-8.45%)	⬇️
server/storage/mvcc/watchable_store.go	84.42% <0.00%> (-5.80%)	⬇️
server/etcdserver/api/v3rpc/lease.go	77.21% <0.00%> (-5.07%)	⬇️
raft/rafttest/node.go	95.00% <0.00%> (-5.00%)	⬇️
server/etcdserver/api/v3rpc/watch.go	82.88% <0.00%> (-4.37%)	⬇️
client/v3/experimental/recipes/key.go	75.34% <0.00%> (-2.74%)	⬇️
client/pkg/v3/transport/listener.go	57.18% <0.00%> (-2.40%)	⬇️
server/etcdserver/api/rafthttp/msgappv2_codec.go	69.56% <0.00%> (-1.74%)	⬇️
... and 13 more

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