Plugin is slow when using conventions with kotlin script in buildSrc

[asodja]

When having a build with shared logic as recommended by Gradle (https://docs.gradle.org/current/samples/sample_sharing_convention_plugins_with_build_logic.html) in buildSrc, plugin can be really slow since there are a lot of gradle files to check/replace variables to.

Maybe a solution is that user could specify gradle files to check.