[Bug]: Service is terminated if scaling fails #1979

> cat fleets/cloud.dstack.yml
type: fleet
name: cloud
nodes: 1
spot_policy: auto

> dstack apply -f fleets/cloud.dstack.yml -y

> cat services/.dstack.yml 
type: service
name: my-service

commands:
  - python -m http.server
port: 8000

replicas: 1

spot_policy: auto

> dstack apply -f services/.dstack.yml --reuse -y

> cat services/.dstack.yml 
type: service
name: my-service

commands:
  - python -m http.server
port: 8000

replicas: 2

spot_policy: auto

> dstack apply -f services/.dstack.yml --reuse -y

 #  BACKEND  REGION    INSTANCE       RESOURCES                   SPOT  PRICE         
 1  gcp      us-west4  e2-standard-2  2xCPU, 8GB, 100.0GB (disk)  yes   $0.0095  busy 

Active run my-service already exists. Detected configuration changes that can be updated in-place: ['replicas']
my-service provisioning completed (running)
Service is published at http://localhost:3000/proxy/services/ilya/my-service/

Serving HTTP on 0.0.0.0 port 8000 (http://localhost:3000/proxy/services/ilya/my-service/) ...
Run failed with error code TERMINATED_BY_SERVER.
Check CLI, server, and run logs for more details

INFO     dstack._internal.server.services.runs:861 run(46bef6)my-service: scaling UP 1 replica(s)
[09:06:24] DEBUG    dstack._internal.server.background.tasks.process_submitted_jobs:99 job(c9251a)my-service-0-1: provisioning has started
[09:06:29] DEBUG    dstack._internal.server.background.tasks.process_submitted_jobs:99 job(c9251a)my-service-0-1: provisioning has started
           DEBUG    dstack._internal.server.background.tasks.process_submitted_jobs:222 job(c9251a)my-service-0-1: reuse instance failed
           INFO     dstack._internal.server.background.tasks.process_runs:330 run(46bef6)my-service: run status has changed RUNNING -> TERMINATING
           INFO     dstack._internal.server.services.jobs:283 job(c9251a)my-service-0-1: job status is FAILED, reason: FAILED_TO_START_DUE_TO_NO_CAPACITY
           DEBUG    dstack._internal.server.services.jobs:192 job(c1f616)my-service-0-0: stopping runner 34.16.243.7
           DEBUG    dstack._internal.server.services.jobs:234 job(c1f616)my-service-0-0: stopping container
[09:07:02] INFO     dstack._internal.server.services.jobs:268 job(c1f616)my-service-0-0: instance 'cloud-0' has been released, new status is IDLE
           INFO     dstack._internal.server.services.jobs:283 job(c1f616)my-service-0-0: job status is TERMINATED, reason: TERMINATED_BY_SERVER
           INFO     dstack._internal.server.services.runs:848 run(46bef6)my-service: run status has changed TERMINATING -> FAILED, reason: JOB_FAILED