[K/N][perf] Workaround broken buildSrc compilation

benchmarksAnalyzer/buildSrc includes sources from K/N's 'build-tools'
subproject. But now these sources depend on the old Kotlin/Native
Gradle plugin (aka tools/kotlin-native-gradle-plugin) causing
compilation errors when building benchmarksAnalyzer/buildSrc.

This patch works around this problem by ignoring the file that
brings this dependency.

kotlin-native/tools/performance-server/ui/buildSrc/build.gradle.kts

@@ -59,6 +59,8 @@ tasks.validatePlugins.configure {
 
 
 sourceSets["main"].withConvention(org.jetbrains.kotlin.gradle.plugin.KotlinSourceSet::class) {
+    kotlin.filter.exclude("**/FileCheckTest.kt")
+
     kotlin.srcDir("../../../../build-tools/src/main/kotlin")
     kotlin.srcDir("../../../../performance/buildSrc/src/main/kotlin")
     kotlin.srcDir("../../../../shared/src/library/kotlin")