Remove health check from Vault client call

What does this MR do?

Remove health check from Vault client call

This health check is redundant: we check two attributes:

1. Initialization
2. Seal status

and ignore the remaining information returned by the health check. In doing so, we incur additional latency to the OpenBao/Vault instance (as we need another round-trip to tell us information the subsequent login will already tell us the same information).

See also:

• https://github.com/openbao/openbao/blob/6d1e0edaf167fac0bc122dd956bb5a439d8782ed/http/sys_health.go#L119-L174
• https://github.com/openbao/openbao/blob/6d1e0edaf167fac0bc122dd956bb5a439d8782ed/vault/request_handling.go#L561-L575
• !5733 (comment 2708003264)
• https://github.com/openbao/openbao/pull/1730
• Fixes #38978 (closed)

Signed-off-by: Alexander Scheel <ascheel@gitlab.com>

Why was this MR needed?

See comment: !5733 (comment 2708003264)

What's the best way to test this MR?

Run a Vault Enterprise instance, point Runner at a Performance Standby instance.