pw_ring_buffer: Decrease test iterations for disco

This decreases the number of iterations of certain tests, to fix running
the tests on the STM32F429i Discovery board. In the future when we have
target traits, this can get increased.

Fixes: pwbug/201
Change-Id: I791dca14c663fc8e3958cdc4b52570810f85a128
diff --git a/pw_ring_buffer/prefixed_entry_ring_buffer_test.cc b/pw_ring_buffer/prefixed_entry_ring_buffer_test.cc
index aad8fac..225eb13 100644
--- a/pw_ring_buffer/prefixed_entry_ring_buffer_test.cc
+++ b/pw_ring_buffer/prefixed_entry_ring_buffer_test.cc
@@ -151,7 +151,9 @@
   SingleEntryWriteReadTest(true);
 }
 
-constexpr size_t kOuterCycles = 5000u;
+// TODO(pwbug/196): Increase this to 5000 once we have a way to detect targets
+// with more computation and memory oomph.
+constexpr size_t kOuterCycles = 50u;
 constexpr size_t kCountingUpMaxExpectedEntries =
     single_entry_test_buffer_size / single_entry_total_size;
 
@@ -295,7 +297,9 @@
   auto entry_data = span(single_entry_buffer);
   size_t i;
 
-  size_t loop_goal = preload ? 500 : 1;
+  // TODO(pwbug/196): Increase this to 500 once we have a way to detect targets
+  // with more computation and memory oomph.
+  size_t loop_goal = preload ? 50 : 1;
 
   for (size_t main_loop_count = 0; main_loop_count < loop_goal;
        main_loop_count++) {