fix(backups): handle slow enable cbt

when VDI.enable_cbt is too slow to answer we may take the snapshot before
cbt is enabled, it fails silently , then take the snapshot , then
on the next backup cbt is enabled , but it fails because cbt started
after the last snapshot, but since cbt was enabled, the data are purged,
leading to a new full backup

@xen-orchestra/backups/_runners/_vmRunners/_AbstractXapi.mjs

@@ -150,7 +150,7 @@ export const AbstractXapi = class AbstractXapiVmBackupRunner extends Abstract {
           try {
             // enable CBT on all disks if possible
             const diskRefs = await xapi.VM_getDisks(vm.$ref)
-            await Promise.all(diskRefs.map(diskRef => xapi.call('VDI.enable_cbt', diskRef)))
+            await Promise.all(diskRefs.map(diskRef => xapi.callAsync('VDI.enable_cbt', diskRef)))
           } catch (error) {
             Task.info(`couldn't enable CBT`, error)
           }

CHANGELOG.unreleased.md

@@ -16,6 +16,7 @@
 ### Bug fixes
 
 > Users must be able to say: “I had this issue, happy to know it's fixed”
+> [Backup] Handle slow cbt_enable leading to full backups
 
 ### Packages to release
 
@@ -33,6 +34,7 @@
 
 <!--packages-start-->
 
+- @xen-orchestra/backups patch
 - @xen-orchestra/log minor
 - @xen-orchestra/web patch
 - @xen-orchestra/web-core minor