Disallow hold->activate-hold->... pattern

[externl]

I think we should simplify in a follow-up PR and eliminate this ability to hold->activate->hold->activate. Why would you ever do that?

_Originally posted by @bernardnormier in https://github.com/zeroc-ice/ice/pull/1676#discussion_r1455942521_

[bernardnormier]

The proposal is:

• a newly created object adapter is in the hold state (just like today)
• when you call activate, it becomes active (just like today)
• once it's active, you can't go back to the hold state. You can only deactivate / destroy this object adapter