fix(kit): Stepper fix flashing styles

[vladimirpotekhin]

Fixes #9632

The first time, when the query list is empty yet, indexOf for all steps returns -1

If we set -1 to the [activeItemIndex] input of the stepper, it will cause the styles to flash since all steps are active for a millisecond.

2024-10-30.11.02.43.mov

[lumberjack-bot]

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BundleMon

Unchanged files (5)

Status	Path	Size	Limits
✅	demo/browser/main.(hash).js	298.46KB	+10%
✅	demo/browser/vendor.(hash).js	255.67KB	+10%
✅	demo/browser/runtime.(hash).js	43.38KB	+10%
✅	demo/browser/styles.(hash).css	19.61KB	+10%
✅	demo/browser/polyfills.(hash).js	11.18KB	+10%

Total files change +9B 0%

Unchanged groups (1)

Status	Path	Size	Limits
✅	demo/browser/*..js	7.22MB	-

Final result: ✅

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