chore: update minimum hardware requirement for vmware ova

[rsmitty]

his PR bumps the minimum hardware family to vmx-15. This corresponds to "ESXi 6.7 U2" and matches the minimum required for anyone deploying the vsphere CSI as shown in this doc. This allows us to bypass an extra step anytime talos is deployed into a vsphere environment.

[rsmitty]

Confirmed working:

[smira]

I'll get it merged and backported to 1.7.1

[smira]

/m