Automated cherry pick of #10468 on release-3.4

[jingyih]

Cherry pick of #10468 on release-3.4.

#10468: etcdserver: remove auth validation loop

[jingyih]

@mitake @gyuho
#10218 was included in 3.4 release. Let's also cherry pick this. So that on server side there is no auth loop on error ErrAuthOldRevision.

[gyuho]

lgtm,

can we highlight this change? (e.g. "please handle err auth old revision error in client side")

[jingyih]

can we highlight this change? (e.g. "please handle err auth old revision error in client side")

From client's perspective, they need to handle ErrAuthOldRevision w/ or w/o this change. The only difference is that w/o the change, server hangs with all CPU cycles used by the loop.

[jingyih]

fmt test failed:

Earlier we merged commit bb5ba14 which has a bad commit title. This will make all future PRs in this branch fail the fmt test.

[xqzhang2015]

@jingyih is this PR blocked by CI?

[jingyih]

can we highlight this change? (e.g. "please handle err auth old revision error in client side")

From client's perspective, they need to handle ErrAuthOldRevision w/ or w/o this change. The only difference is that w/o the change, server hangs with all CPU cycles used by the loop.

@gyuho Given that it is always the case that "client needs to handle ErrAuthOldRevision", do you think this PR needs a changelog highlight?