[Gradle, Test] Fix disable default publications test

Windows has different line endings, so it is not possible to
to seek multiline substrings.

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/HierarchicalMppIT.kt

@@ -1173,7 +1173,8 @@ open class HierarchicalMppIT : KGPBaseTest() {
                     |    </dependency>
                 """.trimMargin()
 
-                if (expectedDependency !in pom) {
+                fun String.asOneLine() = lines().joinToString(" ") { it.trim() }
+                if (expectedDependency.asOneLine() !in pom.asOneLine()) {
                     fail("Expected to find:\n$expectedDependency\nin pom file:\n$pom")
                 }
             }