Incorrect advice when use java-test-fixtures plugin with mixed code(java, kotlin)

**Plugin version**
2.19.0

**Gradle version**
8.14.2

**JDK version**
21

**Describe the bug**
The plugin advices to get rid of the required testFixtures dependency.

**To Reproduce**
There are two modules: A and B. Module B applies the plugin "java-test-fixture" and contains mixed code (Java, Kotlin) in the testFixtures sourceSet. Module A uses testFixtures from Module B.

If you remove the unused Java class from the testFixtures sourceSet, the plugin works as expected.

`./gradlew :android-library:projectHealth`

[TestFixturesReproducer2.zip](https://github.com/user-attachments/files/20988255/TestFixturesReproducer2.zip)

**Expected behavior**
No advices

Unpack TestFixturesReproducer2.zip and run ./gradlew :android-library:projectHealth to reproduce the advice. Compare modules A and B, focusing on B's java-test-fixtures testFixtures sourceSet with mixed Java and Kotlin code. Done means the required testFixtures dependency remains needed and no incorrect advice is emitted.

Written by the indexing model from the issue text.