Add support for `--allow-downgrades` flag in init container

[Vegoo89]

Is your feature request related to a problem?/Why is this needed
Currently I am experiencing issue described in Azure/azure-storage-fuse#1639 and I have to downgrade blobfuse2 to version 2.3.0 on all my AKS nodes until solution is found

Describe the solution you'd like in detail
I would like --allow-downgrades parameter to be setable as Helm chart value for blobfuse and blobfuse2 installation via install-blobfuse-proxy init container

Describe alternatives you've considered
Right now I am settings node.blobfuseProxy.blobfuse2Version to 2.3.0 --allow-downgrades which works, but it can be done in clearer way with minimal effort

Additional context
N/A

[k8s-triage-robot]

The Kubernetes project currently lacks enough contributors to adequately respond to all issues.

This bot triages un-triaged issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue as fresh with /remove-lifecycle stale
• Close this issue with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle stale