tests/common: migrate auth tests #1

[chaochn47]

Please read https://github.com/etcd-io/etcd/blob/main/CONTRIBUTING.md#contribution-flow.

Related to #14041

[codecov-commenter]

Codecov Report

Merging #14998 (008df94) into main (ee9db72) will decrease coverage by 0.06%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main   #14998      +/-   ##
==========================================
- Coverage   74.65%   74.59%   -0.07%     
==========================================
  Files         415      415              
  Lines       34338    34267      -71     
==========================================
- Hits        25636    25560      -76     
- Misses       7062     7070       +8     
+ Partials     1640     1637       -3     

Flag	Coverage Δ
all	74.59% <ø> (-0.07%)	⬇️

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

Impacted Files	Coverage Δ
server/proxy/grpcproxy/register.go	50.00% <0.00%> (-19.77%)	⬇️
client/pkg/v3/tlsutil/tlsutil.go	83.33% <0.00%> (-8.34%)	⬇️
client/v3/leasing/util.go	91.66% <0.00%> (-6.67%)	⬇️
server/storage/mvcc/watchable_store.go	84.78% <0.00%> (-5.44%)	⬇️
server/etcdserver/api/rafthttp/msgappv2_codec.go	69.56% <0.00%> (-3.48%)	⬇️
server/etcdserver/raft.go	88.63% <0.00%> (-2.28%)	⬇️
pkg/schedule/schedule.go	80.45% <0.00%> (-1.15%)	⬇️
server/etcdserver/api/v3rpc/watch.go	86.66% <0.00%> (-0.96%)	⬇️
server/etcdserver/v3_server.go	78.18% <0.00%> (-0.88%)	⬇️
pkg/proxy/server.go	60.67% <0.00%> (-0.34%)	⬇️
... and 10 more

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[ahrtr]

LGTM

Thank you @chaochn47