Remove androidSourceSetLayoutVersion Gradle option

[twyatt]

The Android source layout is version 2 by default and this property was removed in Kotlin 2.0.0.

Example CI warnings:

w: ⚠️ Deprecated Gradle Property 'kotlin.mpp.androidSourceSetLayoutVersion' Used
The `kotlin.mpp.androidSourceSetLayoutVersion` deprecated property is used in your build.
Solutions:
 * It is unsupported, please stop using it.
 * Android Source Set Layout V2 is enabled by default and can't be changed. Leave your questions here https://youtrack.jetbrains.com/issue/KT-82265

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Note

Low Risk
Sample-only Gradle config cleanup with no runtime or build-behavior change beyond silencing deprecation warnings.

Overview
Drops kotlin.mpp.androidSourceSetLayoutVersion=2 from samples/sensortag/gradle.properties.

That Gradle property is deprecated and unsupported in Kotlin 2.0+; Android source set layout v2 is already the default, so the line only triggered CI deprecation warnings.

^{Reviewed by Cursor Bugbot for commit 2741dbe. Configure here.}