lightning failed to connect to tidb when using ipv6 host

[D3Hunter]

Bug Report

like pingcap/tiflow#6135, we should use net.JoinHostPort in:

tidb/br/pkg/lightning/common/util.go

Line 60 in ea5b0ff

dsn := fmt.Sprintf("%s:%s@tcp(%s:%d)/?charset=utf8mb4&sql_mode='%s'&maxAllowedPacket=%d&tls=%s",

PS: we cannot workaround by add square brace to host since when connecting to tidb status port we uses net.JoinHostPort, in which case it'll add square brace twice

tidb/br/pkg/lightning/config/config.go

Line 157 in 323411d

hostPort := net.JoinHostPort(cfg.TiDB.Host, strconv.Itoa(cfg.TiDB.StatusPort))

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