Use nova::compute::image_cache class to set image cache parameters

This change replaces the usage of deprecated image cache parameters of
the nova::compute::libvirt class, by the new nova::compute::image_cache
class which was recently added to puppet-nova.

Depends-on: https://review.opendev.org/#/c/757079/
Depends-on: https://review.opendev.org/#/c/757871/
Change-Id: I85001599cf25ee3c9c82bfc50cb3bd8a71c7bcd9

deployment/nova/nova-compute-container-puppet.yaml

@@ -557,7 +557,7 @@ resources:
               nova::compute::max_disk_devices_to_attach: NovaMaxDiskDevicesToAttach
               nova::compute::libvirt::pmem_namespaces: NovaPMEMMappings
               nova_pmem_namespaces: NovaPMEMNamespaces
-              nova::compute::libvirt::remove_unused_original_minimum_age_seconds: NovaImageCacheTTL
+              nova::compute::image_cache::remove_unused_original_minimum_age_seconds: NovaImageCacheTTL
               nova::compute::libvirt::swtpm_enabled: NovaEnableVTPM
               nova::compute::vgpu::vgpu_types_device_addresses_mapping: NovaVGPUTypesDeviceAddressesMapping
               compute_disable_irqbalance: NovaComputeDisableIrqBalance