fix: remove nil check

[tenthirtyam]

Summary

This pull request includes a small change to the builder/vsphere/clone/step_customize.go file that removes the nil check for w.RunOnceCommandList since len() for a nil slice is defined as zero. The change simplifies the conditional check

packer-plugin-vsphere on fix/remove-nil-check  via 🐹 v1.23.2 
➜ staticcheck builder/vsphere/clone/step_customize.go 
builder/vsphere/clone/step_customize.go:443:5: should omit nil check; len() for []string is defined as zero (S1009)

packer-plugin-vsphere on fix/remove-nil-check  via 🐹 v1.23.2 
➜ staticcheck builder/vsphere/clone/step_customize.go

packer-plugin-vsphere on fix/remove-nil-check  [!] via 🐹 v1.23.2 
➜       

[lbajolet-hashicorp]

That makes sense, the nil check was superfluous as the length of a nil slice is always zero; LGTM!