[test] Shrink vm/dart/profiler_deep_stack_test.

This test is timing out on some configurations.

Change-Id: I42ec230e34b54a078ac52ea9a99782f6b4f88a97
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/459544
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>

Author: rmacnak-google

runtime/tests/vm/dart/profiler_deep_stack_test.dart

@@ -6,7 +6,7 @@
 // VMOptions=--profiler --profile-vm=false
 
 main() {
-  for (var i = 0; i < 10000; i++) {
+  for (var i = 0; i < 100; i++) {
     foo1();
   }
 }