Fix :buildSrc:test by resolving Linux arm64 platform check lazily

BuildPlatform relies on Gradle's native services, which are unavailable
when configuring tasks under ProjectBuilder in unit tests. Evaluating
project.isLinuxArm64() eagerly during test-task configuration made
TestJvmConstraintsPluginTest fail with NativeIntegrationUnavailableException.

Defer the check to execution time via the existing lazy additionalCondition
on ProvideJvmArgsOnJvmLauncherVersion, keeping it out of the configuration path.

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

Author: AlexeyKuznetsov-DD

buildSrc/src/main/kotlin/datadog/gradle/plugin/testJvmConstraints/TestJvmConstraintsPlugin.kt

@@ -90,12 +90,11 @@ class TestJvmConstraintsPlugin : Plugin<Project> {
 
     // Fix for Linux arm64 ByteBuddy error:
     // "Could not self-attach to current VM using external process"
-    if (project.isLinuxArm64()) {
-      conditionalJvmArgs(
-        JavaVersion.VERSION_1_9,
-        listOf("-Djdk.attach.allowAttachSelf=true")
-      )
-    }
+    conditionalJvmArgs(
+      JavaVersion.VERSION_1_9,
+      listOf("-Djdk.attach.allowAttachSelf=true"),
+      project.providers.provider { project.isLinuxArm64() }
+    )
   }
 
   /**