Updates Android samples to use v25.4.0

PiperOrigin-RevId: 936265461

Updates Android samples to use v25.3.0

PiperOrigin-RevId: 919288385

Updates Android samples to use v25.2.0 and Gradle 9.

PiperOrigin-RevId: 901451083

Update Java & Kotlin samples to Google Mobile Ads SDK version 24.4.0

PiperOrigin-RevId: 769650660

Update Java & Kotlin samples to Google Mobile Ads SDK version 24.4.0

PiperOrigin-RevId: 769650660

Creating release v5.8

Creating release v5.7

Creating release v5.6

Creating release v5.3

Creating release v5.2