Set-AzRedisCache tries to list access keys even if just scaling

The `Set-AzRedisCache` cmdlet always tries to get the access keys here:
https://github.com/Azure/azure-powershell/blob/f7f6764da88d2631c44e8f273f0884dd32c61490/src/RedisCache/RedisCache/Commands/SetAzureRedisCache.cs#L136

This has apparently no other reason than to provide the output object as `RedisCacheAttributesWithAccessKeys`.

We use a specific low-privilege **CompliantContributor** ACL role to perform Redis operations. It has permissions to update shard count, but not to read the access keys (and thus the actual customer data).

The command seems to fail today for us:
```
PS C:\Scripts> Set-AzRedisCache -Name trouter-pub-ent-plce-11-ms-v5-0 -ShardCount 5
Set-AzRedisCache: Operation returned an invalid status code 'Forbidden'
```
But it actually does start the scaling operation in the background.

This is confusing and misleading.

Hence, consider making the list access keys operation optional for `Set-AzRedisCache`, so that its failure would not fail the whole command, at least for the operations that do not need them.

Thank you for your consideration

Start in src/RedisCache/RedisCache/Commands/SetAzureRedisCache.cs around line 136, where Set-AzRedisCache retrieves access keys. Reproduce the shard-scaling command with a role that cannot read keys, then verify scaling succeeds without that permission while the command's output remains appropriate.

Written by the indexing model from the issue text.