Backup provider improvements

### The required feature described as a wish

Currently, with the backup implementation, I found the following issues/limitations

**Issue 1**

**Allow multiple backup framework providers at zone level**

**Steps to reproduce the issue**

1. Have a CloudStack environment with One zone and multiple clusters ( KVM. VMware)

2. Configure VEEAM for vmare cluster

https://docs.cloudstack.apache.org/en/4.22.0.0/adminguide/veeam_plugin.html

3. Configure NAS for KVM cluster

https://docs.cloudstack.apache.org/en/4.22.0.0/adminguide/nas_plugin.html#nas-backup-and-recovery-plugin

4. Configure the Global setting "backup.framework.provider.plugin" = veeam.nas

5. Navigate to Service offering > Backup offering

```

2025-12-17 07:24:28,644 ERROR [c.c.a.AlertManagerImpl] (CapacityChecker:[ctx-96786e18]) (logid:0203c46c) Exception in CapacityChecker com.cloud.utils.exception.CloudRuntimeException: Failed to find backup provider by the name: veeam,nas
at org.apache.cloudstack.backup.BackupManagerImpl.getBackupProvider(BackupManagerImpl.java:1656)
at org.apache.cloudstack.backup.BackupManagerImpl.getBackupProvider(BackupManagerImpl.java:1648)
at org.apache.cloudstack.backup.BackupManagerImpl.getBackupStorageUsedStats(BackupManagerImpl.java:2262)
at org.apache.cloudstack.backup.BackupManagerImpl.getBackupStorageUsedStats(BackupManagerImpl.java:176)
at jdk.internal.reflect.GeneratedMethodAccessor417.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:569)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344)

```

**Current behaviour**

Currently, only one Backup framework is allowed per zone, it would be

**Expected behaviour**

It would be great if we could configure the "backup.framework.provider.plugin" at cluster level rather than zone level or support multiple backup providers at zone level

---------------
**Issue 2**

**Associate the backup offerings based on the hypervisor or cluster**

**Steps to reproduce the issue**

1. Have multiple backup offerings one for kvm and one for vmware

2. Navigate to deploy vm form Compute > Select a KVM host or KVM template , all the backup offering are displayed

Similarly, select a VMWare host or vmware template , all the backup offering are displayed

3. Similarly, in the instance view all the backup offerings are displayed

**Expected behaviour**

It would be great if we could display the backup offerings based on the hypervisor or cluster type ( KVM or vmware)

Commencez par les emplacements de BackupManagerImpl.java indiqués dans la stack trace et lisez la documentation liée des plugins Veeam et NAS. Reproduisez la configuration de la zone et examinez les vues de déploiement et d’instance de Compute décrites dans l’issue. C’est terminé lorsque plusieurs providers peuvent coexister comme requis et que les offres de backup sont filtrées selon l’hyperviseur ou le type de cluster.

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