Update StateClass of Liters and Seconds sensor

[Hypfer]

While I haven't received mine yet and therefore can't for sure say that this is in fact an issue (hence Draft PR), while researching the topic, I did find this forum post:

https://community.home-assistant.io/t/automation-only-run-if-available-more-than-30-seconds/707187/13

I can confirm the Hansa Activejet Bluetooth (aka Hasactivejet) is compatible and recognized, as a working well using an ESP bluetooth proxy.

I did notice the water usage and time are registered as state class total by the integration, while they reset to 0 for each new cycle. So they should be state class total_increasing and I used customize.yaml to change it. That will allow to put a utility meter on it to sum total usage.

Looking at the protocol documentation here, I can see that the pulses are 3 bytes and time is 2 bytes.
This would mean max values of ~18 hours and about ~6500 liters, which does sound like it's a lot less than the expected lifetime of a shower head.

Therefore, I am relatively confident that the user is right and TOTAL_INCREASING is the correct state class
Confident enough to open a draft PR at least 🙂

Ref: https://developers.home-assistant.io/docs/core/entity/sensor/#available-state-classes