Enable single address locking in HTTP backend, fixes #23777

[lenaing]

Hi,

This enable single remote endpoint locking, trying to fix #23777.

Now an HTTP backend can just be

terraform {
  backend "http" {
    address = "http://myrestapi.example.com/foo"
    locking = true
  }
}

And the address will then be used for both LOCK and UNLOCK operations.

If lock_address or unlock_address are specified, the HTTP backend use them accordingly as usual, enabling one to override them if required.

Kind regards,

[codecov]

Codecov Report

Merging #26815 into master will increase coverage by 0.01%.
The diff coverage is 54.54%.

Impacted Files	Coverage Δ
backend/remote-state/http/backend.go	82.73% <54.54%> (-2.43%)	⬇️
states/statefile/version4.go	57.96% <0.00%> (-0.24%)	⬇️
terraform/node_resource_apply_instance.go	75.78% <0.00%> (+0.78%)	⬆️
terraform/eval_diff.go	67.43% <0.00%> (+0.91%)	⬆️
terraform/node_resource_plan.go	97.16% <0.00%> (+1.88%)	⬆️

[hashicorp-cla]

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