fix: inaccurate container missing validation hints

Created by: zhaohuiweixiao

Signed-off-by: zhaohuihui zhaohuihui_yewu@cmss.chinamobile.com

What type of PR is this?

/kind bug

What this PR does / why we need it:

When adding an init container, the prompt "Please add at least one container" is still misleading to the user.

Special notes for reviewers:

/assign harrisonliu5

Does this PR introduced a user-facing change?

fix: correct the container missing validation hints