Packer keeps trying to pull a non existent source image

#### Overview of the Issue

I've noticed that one Packer CI job was running for a very long time: more than 30 minutes, when the average job's duration is less than 10 minutes. The following message was logged over and over again:

```
openstack.debian: Image not Active, retrying in 10 seconds
```

I killed the job and found the issue: the image declared in the `external_source_image_url` variable did not exist: the HTTP endpoint was returning a 404 error.

#### Reproduction Steps

Set the `external_source_image_url` variable to a non existent image.

### Plugin and Packer version

Packer 1.7.8
Openstack plugin 1.0.0

### Simplified Packer Buildfile

```
packer {
required_version = "1.7.8"
required_plugins {
openstack = {
version = "1.0.0"
source = "github.com/hashicorp/openstack"
}
}
}

source "openstack" "debian" {
cloud = "dc1"
external_source_image_format = "raw"
external_source_image_url = "http://cdimage.debian.org/cdimage/openstack/10.11.1-20211029/debian-10.11.1-20211029-openstack-amd64.raw"
image_min_disk = "10"
image_name = "bla"
flavor = "packer"
ssh_username = "debian"
}

build {
sources = ["source.openstack.debian"]
}
```
### Operating system and Environment details

Debian Buster

### Log Fragments and crash.log files

```
$ packer build debian.pkr.hcl
116openstack.debian: output will be in this color.
117==> openstack.debian: Loading flavor: packer
118 openstack.debian: Verified flavor. ID: 121d18c3-f0e0-4096-ba60-54c4050ea109
119==> openstack.debian: Creating temporary keypair: packer_61d470f3-fd3e-a797-819b-21b31030b544 ...
120==> openstack.debian: Created temporary keypair: packer_61d470f3-fd3e-a797-819b-21b31030b544
121==> openstack.debian: Creating image using external source image with name packer_61d470f3-fcb1-75b4-1c99-251728853883
122==> openstack.debian: Using disk format raw
123==> openstack.debian: Created image with ID 4964814c-7512-4293-879d-50b5b25b37cb
124==> openstack.debian: Importing External Source Image from URL http://cdimage.debian.org/cdimage/openstack/10.11.1-20211029/debian-10.11.1-20211029-openstack-amd64.raw
125 openstack.debian: Image not Active, retrying in 10 seconds
126 openstack.debian: Image not Active, retrying in 10 seconds
127 openstack.debian: Image not Active, retrying in 10 seconds
128 openstack.debian: Image not Active, retrying in 10 seconds
129 openstack.debian: Image not Active, retrying in 10 seconds
130 openstack.debian: Image not Active, retrying in 10 seconds
131 openstack.debian: Image not Active, retrying in 10 seconds
132 openstack.debian: Image not Active, retrying in 10 seconds
```

Aucun fichier ni test n’est nommé. Commencez par localiser la gestion de external_source_image_url et la boucle de nouvelle tentative de l’état de l’image, puis reproduisez le problème avec une URL qui renvoie 404. La solution doit inclure un échec borné ou terminal avec un message d’erreur clair, au lieu de nouvelles tentatives répétées.

Rédigé par le modèle d'indexation à partir du texte de l'issue.