fix: stabilize ExtensionLifecycleIntegrationTest on Java 8 and 17

Add attachDelayMs=500 and increase checkLines to 10 to match the
established pattern from BTraceFunctionalTests.testExtensionLifecycleClose().

The original checkLines values (2-3) caused the CountDownLatch to hit 0
almost immediately after the BTrace client INFO line, returning from
attach() before the probe had finished executing. The test then triggered
target app shutdown, racing the BTrace output flush. This was
JDK-version-sensitive: Java 8 and 17 lost the race consistently while
Java 11/21/25/26 were fast enough to avoid it.

With checkLines=10 (more than actual output lines), attach() waits up
to the full timeout, giving the probe time to complete. The 500ms attach
delay allows the target JVM to stabilize before probe injection.

<!-- muse-session:impl-20260412-130225 -->

Author: jbachorik

integration-tests/src/test/java/tests/ExtensionLifecycleIntegrationTest.java

@@ -60,11 +60,12 @@ public void reset() {
 
   @Test
   public void testExtensionInitializeAndCloseCalled() throws Exception {
+    attachDelayMs = 500;
     testDynamic(
         "resources.Main",
         "btrace/ExtensionLifecycleFullTest.java",
         new String[] {"extensionCloseTest=true"},
-        2,
+        10,
         new ResultValidator() {
           @Override
           public void validate(String stdout, String stderr, int retcode, String jfrFile) {
@@ -80,11 +81,12 @@ public void validate(String stdout, String stderr, int retcode, String jfrFile)
 
   @Test
   public void testExtensionCloseCalledOnError() throws Exception {
+    attachDelayMs = 500;
     testDynamic(
         "resources.Main",
         "btrace/ExtensionLifecycleErrorTest.java",
         new String[] {"extensionCloseTest=true"},
-        2,
+        10,
         new ResultValidator() {
           @Override
           public void validate(String stdout, String stderr, int retcode, String jfrFile) {
@@ -101,11 +103,12 @@ public void validate(String stdout, String stderr, int retcode, String jfrFile)
 
   @Test
   public void testMultipleExtensionsAllClosed() throws Exception {
+    attachDelayMs = 500;
     testDynamic(
         "resources.Main",
         "btrace/ExtensionLifecycleMultipleTest.java",
         new String[] {"extensionCloseTest=true"},
-        3,
+        10,
         new ResultValidator() {
           @Override
           public void validate(String stdout, String stderr, int retcode, String jfrFile) {