AWS clusters: get allowVolumeExpansion: true by default in StorageClass, or document procedure to update it once

[consideRatio]

We want our StorageClass resource to have allowVolumeExpansion: true, as that makes us able to increase the PVC's requested storage. This is a requirement for the troubleshooting docs here for example.

I believe its not the default at least for AWS based clusters default StorageClass resource, but I think its the default for GCP based clusters.

[yuvipanda]

A lot of our prometheuses were down, so I did this now.

1. Make a script:

   #!/bin/bash
   echo "kubectl patch storageclass gp2 --patch '{\"allowVolumeExpansion\": true}'" | deployer use-cluster-credentials $1

2. Run this against all the clusters. This will just error out in GKE and Azure clusters, and that's fine:

   ls config/clusters | xargs -L1  ./wat.bash

[yuvipanda]

After that, I re-ran https://github.com/2i2c-org/infrastructure/actions/runs/5781619537 again, which completely passed this time. However, dynamic resizing only takes effect when the pod itself is recreated, so am doing that as well now.

[yuvipanda]

Given we've already manually done this for existing clusters, I think for new clusters, we should use #2941 and manage storageclass explicitly. This alleviates r2r concerns that @sgibson91 raised in #2718 as well as allows us to use the cheaper & better gp3 storageclass.