8229707: [TESTBUG] Some Shenandoah tests assume Server VM by default

Reviewed-by: rkennke

Author: shipilev

test/hotspot/jtreg/gc/shenandoah/compiler/TestWriteBarrierClearControl.java

@@ -26,6 +26,7 @@
  * @summary Clearing control during final graph reshape causes memory barrier to loose dependency on null check
  * @key gc
  * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @requires vm.flavor == "server"
  * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:-TieredCompilation
  *                   -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC
  *                   -XX:+UnlockDiagnosticVMOptions -XX:+StressLCM -XX:+StressGCM

test/hotspot/jtreg/gc/shenandoah/options/TestLoopMiningArguments.java

@@ -26,6 +26,7 @@
  * @summary Test that loop mining arguments are sane
  * @key gc
  * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @requires vm.flavor == "server"
  * @library /test/lib
  * @run driver TestLoopMiningArguments
  */