8271891: mark hotspot runtime/Safepoint tests which ignore external VM flags

Backport-of: 6c17e6deb2ab36c3db8577fb6bb2cf2738b58dd4

Author: GoeLin

Diff for: test/hotspot/jtreg/runtime/Safepoint/TestAbortOnVMOperationTimeout.java

@@ -28,6 +28,7 @@
  * @test TestAbortOnVMOperationTimeout
  * @bug 8181143 8269523 8307653
  * @summary Check abort on VM timeout is working
+ * @requires vm.flagless
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management

Diff for: test/hotspot/jtreg/runtime/Safepoint/TestAbortVMOnSafepointTimeout.java

@@ -30,6 +30,7 @@
  * @test TestAbortVMOnSafepointTimeout
  * @summary Check if VM can kill thread which doesn't reach safepoint.
  * @bug 8219584 8227528
+ * @requires vm.flagless
  * @library /testlibrary /test/lib
  * @build jdk.test.whitebox.WhiteBox
  * @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox