Remove unused Gradle dependencies

Remove dependencies flagged as unused by the Dependency Analysis Gradle Plugin
(`./gradlew buildHealth`) and explicitly declared in module build files.

Removals were skipped when the dependency provides transitively something the
module (or a consumer of an `api` dependency) uses directly, as well as for
runtime-only dependencies (element-call-embedded, sentry-android,
rustls-platform-verifier). Dependencies added by the convention plugin helpers
(composeDependencies, testCommonDependencies) are left untouched.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

libraries/mediaplayer/impl/build.gradle.kts

@@ -23,7 +23,6 @@ dependencies {
     implementation(libs.androidx.media3.exoplayer)
 
     implementation(projects.libraries.audio.api)
-    implementation(projects.libraries.core)
     implementation(projects.libraries.di)
 
     implementation(libs.coroutines.core)

libraries/mediaplayer/test/build.gradle.kts

@@ -19,5 +19,4 @@ dependencies {
     implementation(projects.tests.testutils)
 
     implementation(libs.coroutines.test)
-    implementation(libs.test.truth)
 }