test: support mix versions sending snapshot test

[ahrtr]

cc @mitake @ptabor @serathius @spzala

[ahrtr]

cc @tbg and @nvanbenschoten as well.

[codecov-commenter]

Codecov Report

Merging #14707 (eef629e) into main (4d15f50) will decrease coverage by 0.10%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main   #14707      +/-   ##
==========================================
- Coverage   75.56%   75.46%   -0.11%     
==========================================
  Files         457      457              
  Lines       37308    37308              
==========================================
- Hits        28193    28154      -39     
- Misses       7345     7376      +31     
- Partials     1770     1778       +8     

Flag	Coverage Δ
all	75.46% <ø> (-0.11%)	⬇️

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

Impacted Files	Coverage Δ
server/proxy/grpcproxy/register.go	69.76% <0.00%> (-9.31%)	⬇️
client/v3/experimental/recipes/queue.go	58.62% <0.00%> (-6.90%)	⬇️
client/v3/namespace/watch.go	87.87% <0.00%> (-6.07%)	⬇️
raft/rafttest/node.go	95.00% <0.00%> (-5.00%)	⬇️
server/etcdserver/api/rafthttp/msgappv2_codec.go	69.56% <0.00%> (-3.48%)	⬇️
server/etcdserver/api/v3rpc/member.go	93.54% <0.00%> (-3.23%)	⬇️
server/etcdserver/api/v3rpc/interceptor.go	74.47% <0.00%> (-3.13%)	⬇️
server/proxy/grpcproxy/watch.go	92.48% <0.00%> (-2.90%)	⬇️
client/v3/experimental/recipes/key.go	75.34% <0.00%> (-2.74%)	⬇️
client/v3/experimental/recipes/double_barrier.go	68.83% <0.00%> (-2.60%)	⬇️
... and 13 more

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more