fix(load_balancer): lift delete protection when deleting the resource

[nikolauspschuetz]

Closes #1206.

Problem

The delete-protection docs state that a protected resource can still be deleted by Terraform — protection only prevents other API consumers (e.g. the Cloud Console) from deleting it. But hcloud_load_balancer failed with load balancer deletion is protected instead of deleting.

As @apricote noted in the issue, only hcloud_zone_rrset currently lifts protection to make its changes; the other resources don't follow the documented behaviour.

Fix

In resourceLoadBalancerDelete, if the Load Balancer has delete protection enabled, disable it (via the existing setProtection helper) before deleting — mirroring hcloud_zone_rrset. Adds TestAccLoadBalancerResource_DeleteProtectionLifted, which creates a Load Balancer with delete_protection = true and never disables it, so the framework's CheckDestroy must delete a still-protected resource (fails without this change).

Scope

I've scoped this to hcloud_load_balancer — the resource in the issue (and the one that bites the hcloud-cloud-controller-manager use case). Your inventory in #1206 lists the same gap for floating_ip, network, primary_ip, server, volume, and zone. Happy to extend this PR to cover the rest in one coordinated change if you'd prefer that over per-resource PRs — just let me know.

Testing

go build ./..., go vet, and gofmt are clean; the new acceptance test compiles and is skipped without TF_ACC. I haven't run it against a live account in this PR — glad for CI / a maintainer to run it, and I can also run it against my own throwaway project if useful.

AI assistance

Implemented with Claude Code; I directed the change (reusing the in-repo setProtection helper and the zone_rrset pattern) and verified build/vet/test-compile locally.