Update AKS-Attestation example after Gramine PR 884 is merged

[dimakuv]

Must update AKS-Attestation example after gramineproject/gramine#884 is merged. Most probably after Gramine v1.3 is released.

This is because AKS-Attestation example relies on ra-tls-secret-prov.

[dimakuv]

@aneessahib @veenasai2 Pinging you so that you're aware of this.

[dimakuv]

@aneessahib @veenasai2 Pinging again, as v1.3.1 was released.

[aneessahib]

I will pick this up next.

[aneessahib]

@dimakuv - I have simplified this example significantly. Basically reusing most of the stuff from the curated apps work.