Setting default_transition_length to 0s makes fastled_clockless misbehave

### The problem

The `default_transition_length` for the `fastled_clockless` platform is set to 1s by default. It is marked as `Optional` but since it has a default (inherited from the `light` platform) it is always present.

Setting it to 0s (or to a low value such as 1ms) makes it ignore changes until the next command is sent. Instead, the change should take place immediately.

Incidentally, even a command to another led strip using the same platform seems to be enough for the previous (unapplied) change to take place, possibly at the same time as the new change as well. The behaviour looks erratic.

### Which version of ESPHome has the issue?

2024.6.6

### What type of installation are you using?

pip

### Which version of Home Assistant has the issue?

_No response_

### What platform are you using?

ESP32

### Board

Custom board

### Component causing the issue

fastled_clockless

### Example YAML snippet

```yaml
power_supply:
- id: ledstripen1
pin: GPIO25
keep_on_time: 5s
- id: ledstripen2
pin: GPIO26
keep_on_time: 5s

light:
- platform: fastled_clockless
chipset: ws2812b
pin: GPIO23
num_leds: 38
rgb_order: RGB
default_transition_length: 0s # This doesn't work well
name: "Led strip 1"
power_supply: ledstripen1
- platform: fastled_clockless
chipset: ws2812b
pin: GPIO22
num_leds: 38
rgb_order: RGB
default_transition_length: 0s # This doesn't work well
name: "Led strip 2"
power_supply: ledstripen2
```

### Anything in the logs that might be useful for us?

_No response_

### Additional information

I have kept the power_supply entries to match my existing configuration, but note that the power_supply pins are to a power circuit which connects the led strip power to an external power source. The external power source is always on, powering the leds does not require any time, and the problem exists even if the power is kept turned on.