Re-add on_time and off_wait_time to the light_onoff_brightness converter

[marazmarci]

In #8642 it was stated that the on_time and off_wait_time keys were unused in the light_onoff_brightness converter, and they were removed shortly thereafter in 099ea3a.

Recently, after upgrading Z2M, I noticed that some of my light controller automations (which rely on the On With Timed Off command) stopped working. After checking the changelog, I quickly realized what the cause was.

In this PR, I'd like to completely revert these changes.

Some additional context:

In #8175, I added the off_wait_time to this converter, and in the description of that PR, I detailed how the light_onoff_brightness converter can delegate to the on_off converter, which actually uses the on_time and off_wait_time keys.

I was able to successfully use the on_time property for these lights (not a complete list):

• IKEA LED1924G9
• IKEA LED2109G6

[LaurentChardin]

As replied here #8642 (comment)

@Koenkk we should revert it and i will look into another way to address the issue of devices that do not support some of the capabilities.

[Koenkk]

Thanks!