Bug: Single `!Job` specifications execute locally, ignoring `--scheduler` flag

[EdNutting]

When running Gator with --scheduler slurm, standalone !Job specifications execute locally on the control node instead of being submitted to the configured Slurm scheduler. However, !JobGroup specifications with the same jobs correctly submit to Slurm.

Expected Behavior

Jobs specified with !Job should respect the --scheduler slurm command-line flag and submit to the Slurm cluster.

Actual Behavior

• Single !Job: Executes locally on the control node, no Slurm scheduler messages in logs
• !JobGroup with !Job children: Correctly submits to Slurm, logs show "Slurm scheduler using REST API"

Reproduction

Configure Gator with working Slurm REST API

Create a single job spec (/tmp/single_job.yaml):

!Job
  ident: test_single
  command: hostname
  resources:
    - !Cores [1]
    - !Memory [1, GB]

Run: python3 -m gator --scheduler slurm /tmp/single_job.yaml

Result: Job runs locally, no Slurm submission

Create a job group spec (/tmp/group_job.yaml):

!JobGroup
  ident: test_group
  jobs:
    - !Job
        ident: test_node
        command: hostname
        resources:
          - !Cores [1]
          - !Memory [1, GB]

Run: python3 -m gator --scheduler slurm /tmp/group_job.yaml

Result: Job correctly submits to Slurm

Evidence

Single !Job output (no scheduler messages):

[05:10:23] INFO     root                     Running on slurm-ctrl.farm.trustdoubtless.com as PID 1950
           INFO     root                     Layer 'test_single' launching sub-jobs

!JobGroup output (scheduler active):

[05:16:46] INFO     root                     Running on slurm-ctrl.farm.trustdoubtless.com as PID 2088
           INFO     root                     Layer 'test_group' launching sub-jobs
           INFO     root                     Slurm scheduler using REST API version v0.0.41
           INFO     root                     Waiting for 1 dependency tasks to complete

Environment

Gator version: main branch
Slurm version: 24.05.4
Python version: 3.11+

Impact

This makes it impossible to submit simple single-job workflows to Slurm without wrapping them in a !JobGroup, which is counter-intuitive and inconsistent with the --scheduler flag's purpose.