KT-58046 Promote time sources, time marks, measureTime to stable

libraries/stdlib/jvm/test/time/DurationUnitJVMTest.kt

@@ -9,7 +9,6 @@ import java.util.concurrent.TimeUnit
 import kotlin.test.*
 import kotlin.time.*
 
-@OptIn(ExperimentalTime::class)
 class DurationUnitJVMTest {
     @Test
     fun conversionFromTimeUnit() {

libraries/stdlib/jvm/test/time/TimeMarkJVMTest.kt

@@ -9,7 +9,6 @@ import kotlin.test.*
 import kotlin.time.*
 import kotlin.time.Duration.Companion.nanoseconds
 
-@OptIn(ExperimentalTime::class)
 class TimeMarkJVMTest {
 
     @Test