Revert "api_shield_operation v4->v5 migration"

This reverts commit 43f2811.

Author: cortlyons

integration/v4_to_v5/integration_test.go

@@ -9,7 +9,6 @@ import (
 	// Explicitly import the migrations we want to test
 	_ "github.com/cloudflare/tf-migrate/internal/resources/account_member"
 	_ "github.com/cloudflare/tf-migrate/internal/resources/api_shield"
-	_ "github.com/cloudflare/tf-migrate/internal/resources/api_shield_operation"
 	_ "github.com/cloudflare/tf-migrate/internal/resources/api_token"
 	_ "github.com/cloudflare/tf-migrate/internal/resources/custom_pages"
 	_ "github.com/cloudflare/tf-migrate/internal/resources/dns_record"