delay responding to `SubscribeState` when `SERVER_ACTIVE` received

[ZZiigguurraatt]

When using lndinit wait-ready (https://github.com/lightninglabs/lndinit?tab=readme-ov-file#wait-ready) through litd, it proxies the query and response for SubscribeState through without any filtering because this is an unprotected endpoint. However, this can result in lndinit wait-ready returning too early, before the litd proxy has time to realize lnd is ready and that it should start allowing other queries through.

So for example,

https://github.com/lightninglabs/lndinit/blob/a21e308c8be581652eabbaeea0837c0167397bde/example-init-wallet-k8s.sh#L90-L93

will fail because it runs too quickly.

I think litd should be smart enough to delay responding to SubscribeState when it receives a SERVER_ACTIVE until litd has had a chance to recognize this itself too.