vendor: add missing grpc files

[YoyinZyc]

Added missing files when I updated grpc version in pr #11522. It should fix recent go get issues.
cc @spzala

[codecov-io]

Codecov Report

Merging #11557 into master will increase coverage by 0.09%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #11557      +/-   ##
==========================================
+ Coverage   64.48%   64.58%   +0.09%     
==========================================
  Files         403      403              
  Lines       38097    38097              
==========================================
+ Hits        24568    24605      +37     
+ Misses      11882    11849      -33     
+ Partials     1647     1643       -4

Impacted Files	Coverage Δ
auth/options.go	67.5% <0%> (-25%)	⬇️
pkg/adt/interval_tree.go	84.21% <0%> (-3.01%)	⬇️
etcdserver/api/v2http/client.go	84.3% <0%> (-1.21%)	⬇️
clientv3/retry_interceptor.go	68.31% <0%> (-1%)	⬇️
clientv3/leasing/kv.go	89.03% <0%> (-0.67%)	⬇️
clientv3/watch.go	91.44% <0%> (-0.63%)	⬇️
etcdserver/cluster_util.go	57.31% <0%> (ø)	⬆️
pkg/transport/timeout_conn.go	80% <0%> (ø)	⬆️
etcdserver/v3_server.go	73.29% <0%> (+0.64%)	⬆️
etcdserver/api/v3rpc/watch.go	80.39% <0%> (+0.65%)	⬆️
... and 8 more

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[spzala]

lgmt

[spzala]

@YoyinZyc thanks and yes it should fix #11532 and related dups.
/cc @jingyih @xiang90 @gyuho