Fix find usages tests in 173 (run via ProgressIndicator)

idea/tests/org/jetbrains/kotlin/findUsages/AbstractFindUsagesTest.kt

@@ -28,6 +28,9 @@ import com.intellij.lang.properties.psi.PropertiesFile
 import com.intellij.lang.properties.psi.Property
 import com.intellij.openapi.editor.markup.TextAttributes
 import com.intellij.openapi.extensions.Extensions
+import com.intellij.openapi.progress.ProgressIndicator
+import com.intellij.openapi.progress.ProgressManager
+import com.intellij.openapi.progress.Task
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.ui.Messages
 import com.intellij.openapi.util.io.FileUtil
@@ -308,12 +311,13 @@ internal fun findUsages(
                 }
             }
             else {
-                // run in another thread to test read-action assertions
-                val thread = Thread {
-                    handler.processElementUsages(psiElement, processor, options)
-                }
-                thread.start()
-                thread.join()
+                ProgressManager.getInstance().run(object : Task(project, "",false) {
+                    override fun isModal() = true
+
+                    override fun run(indicator: ProgressIndicator) {
+                        handler.processElementUsages(psiElement, processor, options)
+                    }
+                })
             }
         }