Comments to the question give good reasoning why NOT to do it in the code - use the same type of the database in your tests.

But if you still want to do it - I could only think of putting this logic both in the db context and entity type configuration. Please see demo below

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
using Microsoft.EntityFrameworkCore.SqlServer.Infrastructure.Internal;
using Microsoft.Extensions.DependencyInjection;

var serviceCollection = new ServiceCollection();
serviceCollection.AddDbContext<AppDbContext>(builder => builder.UseSqlServer("xxx"));
var serviceProvider = serviceCollection.BuildServiceProvider();
var dbContext = serviceProvider.GetRequiredService<AppDbContext>();
// trigger entity configuration
dbContext.Orders.ToList();

public class Orders
{
    public int Id { get; set; }
    public byte[] RowVersion { get; set; }
}

public class OrderConfiguration : IEntityTypeConfiguration<Orders>
{
    private readonly string provider;

    public OrderConfiguration(string provider)
    {
        this.provider = provider;
    }
    
    public void Configure(EntityTypeBuilder<Orders> builder)
    {
        builder.HasKey(x => x.Id);
        
        if (provider == "SqlServer")
        {
            builder.Property(x => x.RowVersion)
                .IsRequired(true)
                .IsRowVersion()
                .IsConcurrencyToken()
                ;
        }
    }
}

public class AppDbContext : DbContext
{
    public DbSet<Orders> Orders { get; set; }

    public AppDbContext(DbContextOptions<AppDbContext> options) : base(options)
    {
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        string provider = null;
        if (Database.IsSqlServer())
        {
            provider = "SqlServer";
        }

        // do this or load different configuration type for each provider
        modelBuilder.ApplyConfiguration(new OrderConfiguration(provider)); 
        
        base.OnModelCreating(modelBuilder);
    }
}