builtin/terraform: provide empty config schema to avoid spurious ERROR log (#38183)

* builtin/terraform: provide empty config schema to avoid spurious ERROR log

The builtin terraform provider returned a nil Body in its provider config
schema, which caused AttachSchemaTransformer to emit an ERROR-level log
message ("No provider config schema available for provider[terraform.io/
builtin/terraform]") even though the provider works correctly. This is
confusing for users who filter logs by severity, especially in CI pipelines.

Set the provider config schema to an empty configschema.Block{} so that
AttachSchemaTransformer finds a valid (but empty) schema and skips the
error log. This matches the maintainer's suggested fix in #34207.

Fixes #34207

* Add changelog entry for builtin provider schema fix

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Remove changelog entry per reviewer feedback

Not an end-user facing change, so no changelog needed.

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

internal/builtin/providers/terraform/provider.go

@@ -10,6 +10,7 @@ import (
 	tfaddr "github.com/hashicorp/terraform-registry-address"
 	"github.com/zclconf/go-cty/cty"
 
+	"github.com/hashicorp/terraform/internal/configs/configschema"
 	"github.com/hashicorp/terraform/internal/providers"
 )
 
@@ -26,7 +27,7 @@ func NewProvider() providers.Interface {
 // GetSchema returns the complete schema for the provider.
 func (p *Provider) GetProviderSchema() providers.GetProviderSchemaResponse {
 	resp := providers.GetProviderSchemaResponse{
-		Provider: providers.Schema{},
+		Provider: providers.Schema{Body: &configschema.Block{}},
 		ServerCapabilities: providers.ServerCapabilities{
 			MoveResourceState: true,
 		},

internal/builtin/providers/terraform/provider_test.go

@@ -67,3 +67,13 @@ func TestMoveResourceState_NonExistentResource(t *testing.T) {
 		t.Fatal("expected diagnostics")
 	}
 }
+
+func TestGetProviderSchema_ProviderConfigNotNil(t *testing.T) {
+	provider := &Provider{}
+	resp := provider.GetProviderSchema()
+
+	if resp.Provider.Body == nil {
+		t.Fatal("provider config schema body should not be nil; a nil body causes " +
+			"a spurious ERROR-level log message in AttachSchemaTransformer")
+	}
+}