[ws-cluster] Two API bugs

[geropl]

Bug description

• ./gpctl clusters list always returns governed=true
• ./gpctl clusters register ... --hint-preferability=dontschedule

Steps to reproduce

Use the commands above against a Gitpod cluster.

Expected behavior

No response

Example repository

No response

[csweichel]

governed=true is fixed in #3793

[geropl]

Fixed with #3793