8386345: Remove redundant @requires from TestGarbageCollectionEventWithZMinor

Backport-of: d46298d681f78d8f16ee4ed8031520dcd76d3c4c

Author: GoeLin

test/jdk/jdk/jfr/event/gc/collection/TestGarbageCollectionEventWithZMinor.java

@@ -41,7 +41,6 @@
  * @test
  * @requires vm.flagless
  * @requires vm.hasJFR & vm.gc.Z
- * @requires vm.flagless
  * @library /test/lib /test/jdk
  * @build jdk.test.whitebox.WhiteBox
  * @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox