Make tier changes seamless

[roflcoopter]

Hi all,
I have run into similar issue, but related to migration from plain segments to tier1.

1. Set up bare minimum config, with no storage section in the config. Confirmed that the live stream worked.
2. After a few minutes, set up storage with tiers. At this point, timeline works too.
3. After few more minutes timeline does not work any more. The log gives a ton of 404 messages about files/segments/front_doorbell/init.mp4.

At this point, there is no init.mp4 by this path, but there is init.mp4 under tier1/...

Later, init.mp4 appeared under /segments/ too, but I still kept getting 404.

Relevant parts from my config:

storage:
  recorder:
    tiers:
      - path: /tier1
        continuous:
          max_size:
            gb: 10
          max_age:
            days: 1
        events:
          max_size:
            gb: 1
          max_age:
            days: 1
      - path: /tier2
        continuous:
          max_size:
            gb: 100
          max_age:
            days: 30
        events:
          max_size:
            gb: 100
          max_age:
            days: 365
  snapshots:
    tiers:
      - path: /tier1
        max_size:
          gb: 100
        max_age:
          days: 30

And from docker compose:

    volumes:
      - ${VOLUMES}/viseron/segments:/segments
      - ${VOLUMES}/viseron/snapshots:/snapshots
      - ${VOLUMES}/viseron/thumbnails:/thumbnails
      - ${VOLUMES}/viseron/event_clips:/event_clips
      - ${VOLUMES}/viseron/config:/config
      - ${VOLUMES}/viseron/tier1:/tier1
      - ${VOLUMES}/viseron/tier2:/tier2

Version: 3.2.3 - f9ebd37

I then installed viseron from scratch while keeping the config, and everything works fine so far.

Given all that my wild guess would be that something is off with migrating from no-tiers setup to the one with tiers.

Originally posted by @matvey00z in #1020