Reduce runtime of compact_on_deletion_collector_test (#4117)

Summary:
This test routinely exceeds the FB contbuild test timeout of 10 minutes,
due to the large number of iterations. The large number (mainly due to
100 randomly selected window sizes) does not seem to add any value.
Reduce it to allow the test to finish in < 10 mins.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4117

Differential Revision: D8815646

Pulled By: anand1976

fbshipit-source-id: 260690d24f444767ad93b039dec3ae8b9cdd1843

utilities/table_properties_collectors/compact_on_deletion_collector_test.cc

@@ -40,7 +40,7 @@ int main(int /*argc*/, char** /*argv*/) {
   // randomize tests
   rocksdb::Random rnd(301);
   const int kMaxTestSize = 100000l;
-  for (int random_test = 0; random_test < 100; random_test++) {
+  for (int random_test = 0; random_test < 50; random_test++) {
     int window_size = rnd.Uniform(kMaxTestSize) + 1;
     int deletion_trigger = rnd.Uniform(window_size);
     window_sizes.emplace_back(window_size);