The readonly port could be disabled.
Since we are only using the /healthz endpoint,
we can use the healthz port for this.
Change-Id: Ie0e05a5ab4ec6f51e4d3c63226aa23c1b3a69956
Now the following flags have no effect and would be removed in v1.24:
* `--port`
* `--address`
The insecure port flags `--port` may only be set to 0 now.
Signed-off-by: Jian Zeng <zengjian.zj@bytedance.com>