[Build] Add jUnit dependencies in testApiJUnit5 to the implementation configuration

Adding these dependencies to the `api` configuration pollutes classpath for each dependant modules even if it doesn't need them. Instead, the dependencies should be declared more granularly if they're required
#KTI-1349 In Progress

prepare/compiler-embeddable/build.gradle.kts

@@ -22,7 +22,7 @@ dependencies {
     runtimeOnly(commonDependency("org.jetbrains.kotlin:kotlin-reflect")) { isTransitive = false }
     runtimeOnly(project(":kotlin-daemon-embeddable"))
     runtimeOnly(commonDependency("org.jetbrains.intellij.deps", "trove4j"))
-    testApi(libs.junit4)
+    testImplementation(libs.junit4)
     testApi(project(":kotlin-test:kotlin-test-junit"))
     testCompilationClasspath(kotlinStdlib())
 }