Sessions in the PREPARED status disappear and reappear after scheduling delays, hurting UX

[achimnol]

After introduction of the PREPARED session status (lablup/backend.ai#2721) to decouple the image pulling process from the container creation process, there are some delays before proceeding to the CREATING status depending on the scheduler invocation frequency and timing.

The current webui (24.12.0-alpha.2.1) does not display the PREPARED sessions in the default "running" sessions tab.

So all new sessions are first displayed as PENDING, they are gone away, and after a while they reappear once they enter CREATING/RUNNING.

I believe we should also display PREPARED sessions, or need to split the view for pre-RUNNING sessions using an additional tab or a separate notification stream.

Related:

• feat: Support new status PREPARED of session and kernel #2848
• feat: Add CREATING session status #2849

[ironAiken2]

After WebUI #2854 PR with manager version after 24.12.0 + , the PREPARED session is also showing up in the running session tab. (pending -> preparing -> prepared -> creating -> created -> running)