Fix CRDs to prepare for controller-runtime upgrade

Bumping controller-runtime from 0.14.1 to 0.14.4 (#2261) seem to break our integration test:

```
      unable to install CRDs onto control plane: unable to create CRD instances: unable to create CRD "ephemeralrunners.actions.github.com": CustomResourceDefinition.apiextensions.k8s.io "ephemeralrunners.actions.github.com" is invalid: [spec.validation.openAPIV3Schema.properties[spec].properties[spec].properties[volumes].items.properties[ephemeral].properties[volumeClaimTemplate].properties[spec].properties[resources].properties[claims].x-kubernetes-list-type: Required value: must be map if x-kubernetes-list-map-keys is non-empty, spec.validation.openAPIV3Schema.properties[spec].properties[spec].properties[ephemeralContainers].items.properties[resources].properties[claims].x-kubernetes-list-type: Required value: must be map if x-kubernetes-list-map-keys is non-empty, spec.validation.openAPIV3Schema.properties[spec].properties[spec].properties[containers].items.properties[resources].properties[claims].x-kubernetes-list-type: Required value: must be map if x-kubernetes-list-map-keys is non-empty, spec.validation.openAPIV3Schema.properties[spec].properties[spec].properties[initContainers].items.properties[resources].properties[claims].x-kubernetes-list-type: Required value: must be map if x-kubernetes-list-map-keys is non-empty]
```

The offending field, "x-kubernetes-list-map-keys", was already there before the upgrade.

We previously fixed a similar issue for "x-kubernetes-list-type" in #2132. At that time we already had "x-kubernetes-list-map-keys" but the integration test didn't fail.

Presuming this might be due to new K8s dependencies or controller-runtime envtest change, I'd like to just drop the field like we've already done for -type field in #2132.

Ref #2132
Ref #2261