Remove @PublishedApi from unwrap to comply with new compiler restriction (#3810)

In KT-58551 we require all annotations from expect declaration to be
present on actual.

Currently, `unwrap` is not called from public inline functions.
We can safely remove it.

Co-authored-by: Roman Efremov <roman.efremov@jetbrains.com>

Author: merfemor

kotlinx-coroutines-core/common/src/internal/StackTraceRecovery.common.kt

@@ -40,7 +40,6 @@ internal expect suspend inline fun recoverAndThrow(exception: Throwable): Nothin
  * The opposite of [recoverStackTrace].
  * It is guaranteed that `unwrap(recoverStackTrace(e)) === e`
  */
-@PublishedApi // published for the multiplatform implementation of kotlinx-coroutines-test
 internal expect fun <E: Throwable> unwrap(exception: E): E
 
 internal expect class StackTraceElement