Prevent basic authentication from popping up

[JohnNiang]

What type of PR is this?

/kind improvement
/kind api-change
/area core
/milestone 2.10.x

What this PR does / why we need it:

See #4547 for more.

This PR creates header WWW-Authenticate like FormLogin realm="console" instead of Basic realm="realm" while unauthorized.

Which issue(s) this PR fixes:

Fixes #4547

Special notes for your reviewer:

curl --head 'http://localhost:8090/actuator/info'
HTTP/1.1 401 Unauthorized
transfer-encoding: chunked
Vary: Origin
Vary: Access-Control-Request-Method
Vary: Access-Control-Request-Headers
WWW-Authenticate: FormLogin realm="console"
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Content-Type-Options: nosniff
X-Frame-Options: DENY
X-XSS-Protection: 0
Referrer-Policy: no-referrer

Does this PR introduce a user-facing change?

防止浏览器弹出基础认证弹窗

[ruibaby]

/lgtm

[guqing]

/approve

[f2c-ci-robot]

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