Code review comment for ~jchittum/ubuntu/+source/lxd-installer:devel-channel-version-selector

2 issues I think here.

1. Don't we expect noble or any non jammy/focal release to be `latest/stable` channel?

I think that warrants a default setting that clears channel_suffix to "stable"

2. No current channels exists with format `stable/ubuntu-XX.YY` We probably need those channels for lxd snap to show up before landing this right?

```
snap-id: J60k4JY0HppjwOjW8dZdYc8obXKxujRu
tracking: 5.16/stable
refresh-date: 2023-08-30
channels:
  latest/stable: 5.19-8635f82 2023-11-22 (26200) 159MB -
  latest/candidate: 5.19-b8ce621 2023-12-04 (26415) 158MB -
  latest/beta: ↑
  latest/edge: git-fdc3dc6 2023-12-05 (26461) 158MB -
  5.19/stable: 5.19-31ff7b6 2023-10-20 (26093) 159MB -
  5.19/candidate: ↑
  5.19/beta: ↑
  5.19/edge: ↑
  5.18/stable: 5.18-762f582 2023-09-26 (25748) 189MB -
  5.18/candidate: ↑
  5.18/beta: ↑
  5.18/edge: ↑
  5.17/stable: 5.17-e5ead86 2023-08-29 (25505) 184MB -
  5.17/candidate: ↑
  5.17/beta: ↑
  5.17/edge: ↑
  5.16/stable: 5.16-f2b0200 2023-07-26 (25353) 183MB -
  5.16/candidate: ↑
  5.16/beta: ↑
  5.16/edge: ↑
  5.15/stable: 5.15-3fe7435 2023-06-28 (25086) 181MB -
  5.15/candidate: ↑
  5.15/beta: ↑
  5.15/edge: ↑
  5.0/stable: 5.0.2-838e1b2 2023-01-25 (24322) 117MB -
  5.0/candidate: 5.0.2-838e1b2 2023-01-18 (24322) 117MB -
  5.0/beta: ↑
  5.0/edge: git-250277b 2023-12-05 (26449) 126MB -
  4.0/stable: 4.0.9-a29c6f1 2022-12-04 (24061) 96MB -
  4.0/candidate: 4.0.9-a29c6f1 2022-12-02 (24061) 96MB -
  4.0/beta: ↑
  4.0/edge: git-407205d 2022-11-22 (23988) 96MB -
  3.0/stable: 3.0.4 2019-10-10 (11348) 55MB -
  3.0/candidate: 3.0.4 2019-10-10 (11348) 55MB -
  3.0/beta: ↑
  3.0/edge: git-81b81b9 2019-10-10 (11362) 55MB -
installed: 5.16-f2b0200 (25353) 183MB -
```