fix: Don't use the the shared tempdir as it is shared for every test

This causes all tests to use the same user preference folder,
possibly increasing the chance of this issue happening.

Author: bric3

dd-java-agent/agent-ci-visibility/civisibility-test-fixtures/src/main/groovy/datadog/trace/civisibility/CiVisibilitySmokeTest.groovy

@@ -6,6 +6,7 @@ import datadog.trace.api.config.CiVisibilityConfig
 import datadog.trace.api.config.GeneralConfig
 import datadog.trace.api.config.TraceInstrumentationConfig
 import datadog.trace.api.config.TracerConfig
+import java.nio.file.Paths
 import spock.lang.Shared
 import spock.lang.Specification
 import spock.lang.TempDir
@@ -28,10 +29,6 @@ abstract class CiVisibilitySmokeTest extends Specification {
   @TempDir
   protected Path prefsDir
 
-  @Shared
-  @TempDir
-  protected Path prefsDirShared
-
   protected static String buildJavaHome() {
     if (Jvm.current.isJava8()) {
       return System.getenv("JAVA_8_HOME")
@@ -111,10 +108,16 @@ abstract class CiVisibilitySmokeTest extends Specification {
    * `setupSpec()`.
    */
   protected String preventJulPrefsFileLock() {
-    String prefsPath = (prefsDir ?: prefsDirShared).toAbsolutePath()
+    String prefsPath = (prefsDir ?: tempUserPrefsPath()).toAbsolutePath()
     return "-Djava.util.prefs.userRoot=$prefsPath".toString()
   }
 
+  private static Path tempUserPrefsPath() {
+    String uniqueId = "${System.currentTimeMillis()}_${System.nanoTime()}_${Thread.currentThread().id}"
+    Path prefsPath = Paths.get(System.getProperty("java.io.tmpdir"), "gradle-test-userPrefs", uniqueId)
+    return prefsPath
+  }
+
   protected verifyEventsAndCoverages(String projectName, String toolchain, String toolchainVersion, List<Map<String, Object>> events, List<Map<String, Object>> coverages, List<String> additionalDynamicTags = []) {
     def additionalReplacements = ["content.meta.['test.toolchain']": "$toolchain:$toolchainVersion"]