Revert changes from 6e67e1e78d in Gradle integration tests

To fix the JPS build.

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

@@ -354,11 +354,11 @@ abstract class BaseGradleIT {
 
         val errors = "(?m)^.*\\[ERROR] \\[\\S+] (.*)$".toRegex().findAll(output)
         val errorMessage = buildString {
-            appendLine("Gradle build failed")
+            appendln("Gradle build failed")
-            appendLine()
+            appendln()
             if (errors.any()) {
-                appendLine("Possible errors:")
+                appendln("Possible errors:")
-                errors.forEach { match -> appendLine(match.groupValues[1]) }
+                errors.forEach { match -> appendln(match.groupValues[1]) }
             }
         }
         fail(errorMessage)
@@ -669,10 +669,10 @@ Finished executing task ':$taskName'|
             }
 
         val xmlString = buildString {
-            appendLine("<?xml version=\"1.0\" encoding=\"UTF-8\"?>")
+            appendln("<?xml version=\"1.0\" encoding=\"UTF-8\"?>")
-            appendLine("<results>")
+            appendln("<results>")
             files.forEach {
-                appendLine(
+                appendln(
                     it.readText()
                         .trimTrailingWhitespaces()
                         .replace(projectDir.absolutePath, "/\$PROJECT_DIR$")
@@ -680,7 +680,7 @@ Finished executing task ':$taskName'|
                         .replace("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n", "")
                 )
             }
-            appendLine("</results>")
+            appendln("</results>")
         }
 
         val doc = SAXBuilder().build(xmlString.reader())

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

@@ -70,7 +70,7 @@ class KotlinGradleIT : BaseGradleIT() {
         wd1.deleteRecursively()
         if (wd1.exists()) {
             val files = buildString {
-                wd1.walk().forEach { appendLine("  " + it.relativeTo(wd1).path) }
+                wd1.walk().forEach { appendln("  " + it.relativeTo(wd1).path) }
             }
             error("Some files in $wd1 were not removed:\n$files")
         }

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

@@ -52,11 +52,11 @@ class MppHighlightingTestDataWithGradleIT : BaseGradleIT() {
 
         // create Gradle Kotlin source sets for project roots:
         val scriptCustomization = buildString {
-            appendLine()
+            appendln()
-            appendLine("kotlin {\n    sourceSets {")
+            appendln("kotlin {\n    sourceSets {")
             sourceRoots.forEach { sourceRoot ->
                 if (sourceRoot.kotlinSourceSetName != "commonMain") {
-                    appendLine(
+                    appendln(
                         """        create("${sourceRoot.kotlinSourceSetName}") {
                           |            dependsOn(getByName("commonMain"))
                           |            listOf(${cliCompiler.targets.joinToString { "$it()" }}).forEach { 
@@ -67,7 +67,7 @@ class MppHighlightingTestDataWithGradleIT : BaseGradleIT() {
                         """.trimMargin()
                     )
                 } else {
-                    appendLine("    // commonMain source set used for common module")
+                    appendln("    // commonMain source set used for common module")
                 }
             }
 
@@ -76,11 +76,11 @@ class MppHighlightingTestDataWithGradleIT : BaseGradleIT() {
                 sourceRoot.dependencies.forEach { dependency ->
                     sourceRoots.find { it.qualifiedName == dependency }?.let { depSourceRoot ->
                         val depSourceSet = depSourceRoot.kotlinSourceSetName
-                        appendLine("""        getByName("${sourceRoot.kotlinSourceSetName}").dependsOn(getByName("$depSourceSet"))""")
+                        appendln("""        getByName("${sourceRoot.kotlinSourceSetName}").dependsOn(getByName("$depSourceSet"))""")
                     }
                 }
             }
-            appendLine("    }\n}")
+            appendln("    }\n}")
         }
 
         gradleBuildScript().appendText("\n" + scriptCustomization)

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

@@ -39,7 +39,7 @@ fun runProcess(
         if (options?.forceOutputToStdout ?: false) {
             println(it)
         }
-        sb.appendLine(it)
+        sb.appendln(it)
     }
     val exitCode = process.waitFor()