test(extend-app-start): Drop redundant getExtendedAppStartSpan finished test

After getExtendedAppStartSpan switched to getFinishDate(), the
"after the span finished" case exercises the same branch as the
reentrancy test (finishDate set -> NoOp); the isFinished stub was inert.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: buenaflor

sentry-android-core/src/test/java/io/sentry/android/core/AppStartExtensionTest.kt

@@ -233,17 +233,6 @@ class AppStartExtensionTest {
     assertSame(NoOpSpan.getInstance(), ext.extendedAppStartSpan)
   }
 
-  @Test
-  fun `getExtendedAppStartSpan returns NoOpSpan after the span finished`() {
-    val ext = extension(windowOpen = true)
-    val span = mock<ISpan>()
-    whenever(span.isFinished).thenReturn(true)
-    whenever(span.finishDate).thenReturn(SentryNanotimeDate())
-    ext.registerHandOver(span = span)
-    ext.extendAppStart()
-    assertSame(NoOpSpan.getInstance(), ext.extendedAppStartSpan)
-  }
-
   @Test
   fun `getExtendedAppStartSpan returns NoOpSpan once the finish date is set even if still unfinished`() {
     // Same waitForChildren reentrancy as getExtendedEndTime: the finish timestamp is set before the