Incomplete ClusterBootstrap method

[nurzhan-saktaganov]

Original: KaymeKaydex/go-vshard-router#115

ClusterBootstrap method doesn't fully reflect what tnt vshard router'r cluster_bootstrap does.
Use tnt vshard router as reference to fix that:
https://github.com/tarantool/vshard/blob/e1c806e1d3d2ce8a4e6b4d498c09051bf34ab92a/vshard/router/init.lua#L1642

go-vshard-router/vshard.go

Lines 386 to 397 in 0a8677f

	func (r *Router) ClusterBootstrap(ctx context.Context, ifNotBootstrapped bool) error {
	rssToBootstrap := make([]Replicaset, 0, len(r.idToReplicaset))
	var lastErr error
	for _, rs := range r.idToReplicaset {
	rssToBootstrap = append(rssToBootstrap, *rs)
	}
	err := CalculateEtalonBalance(rssToBootstrap, r.cfg.TotalBucketCount)
	if err != nil {
	return err
	}