exp show: output executor info for successful exps when available

[pmrowla]

• ❗ I have followed the Contributing to DVC checklist.

• 📖 If this PR requires documentation updates, I have created a separate PR (or issue, at least) in dvc.org and linked it here.

Thank you for the contribution - we'll try to review it as soon as possible. 🙏

Should close #9425
related: #9442

For sucessfully run queued experiments, dvc exp show --json will now include executor info if it's still available (i.e. logs haven't been removed with dvc queue remove)

"experiments": [
      {
        "revs": [
          {
            "rev": "cb9a2cbf153a84f29d6c0b811e3b834054931459",
            "name": "timid-pear",
            "data": {
              ...
              },
              "deps": {
                ...
                }
              },
              "outs": {
                ...
              },
              "meta": {}
            },
            "error": null,
            "experiments": null
          }
        ],
        "executor": {
          "state": "success",
          "name": "dvc-task",
          "local": {
            "root": null,
            "log": "/Users/pmrowla/git/example-get-started/.dvc/tmp/exps/run/af02dc1c0758c910a7c643194e5ba3f2687f463f/af02dc1c0758c910a7c643194e5ba3f2687f463f.out",
            "pid": 16615,
            "returncode": 0,
            "task_id": "af02dc1c0758c910a7c643194e5ba3f2687f463f"
          }
        },
        "name": "timid-pear"
      },
...

note that:

• pid is listed but will no longer be valid since the run finished
• root is unavailable since the tempdir used for execution is removed on exp completion (but the logs are available and stored in a separate location)

executor will still be null for successful workspace and --temp runs since we do not preserve any executor state or logs in those cases (handling logs for these cases will be done separately, but once those are available they will work the same as the dvc-task queued exps here)

[codecov]

Codecov Report

Attention: 10 lines in your changes are missing coverage. Please review.

Comparison is base (df5b582) 90.49% compared to head (9c55949) 90.47%.

Files	Patch %	Lines
dvc/repo/experiments/queue/celery.py	28.57%	9 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10239      +/-   ##
==========================================
- Coverage   90.49%   90.47%   -0.03%     
==========================================
  Files         493      493              
  Lines       37665    37680      +15     
  Branches     5461     5465       +4     
==========================================
+ Hits        34084    34090       +6     
- Misses       2954     2962       +8     
- Partials      627      628       +1     

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[mattseddon]

Looks like this works 👍🏻:

Screen.Recording.2024-01-17.at.3.10.04.pm.mov

Sorry to be that guy but... any reason there are no tests?

[pmrowla]

The underlying code for collecting all of this info is already tested (this PR doesn't actually do anything new other than exposing it in the output)

[dberenbaum]

@pmrowla Is it ready to merge?