Remove enos provider from build_local enos module (#17102)

- The provider isn't needed and there is an error in the source
   anyways.

❯ enos scenario validate managed_keys
Scenario: managed_keys [arch:arm64 backend:raft builder:local distro:ubuntu edition:ent seal:awskms]
  Generate: ✅
 Init: ❌

Error: Invalid provider registry host

The host "hashicorp.com" given in in provider source address
"hashicorp.com/qti/enos" does not offer a Terraform provider registry.

enos/modules/build_local/main.tf

@@ -1,11 +1,3 @@
-terraform {
-  required_providers {
-    enos = {
-      source = "hashicorp.com/qti/enos"
-    }
-  }
-}
-
 variable "bundle_path" {
   type    = string
   default = "/tmp/vault.zip"