[tracing] Update kDefaultSMBPageSizeBytes to 4*1024 on all platforms

This has been the config on canary/dev for a few weeks now, and
it improves missing thread issues.

Bug: 40574594
Change-Id: I2a0b743c9da8e66079d691f28e8ce493b79abaa9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6408572
Reviewed-by: Mikhail Khokhlov <khokhlov@google.com>
Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1457557}

services/tracing/public/cpp/tracing_features.h

@@ -39,14 +39,7 @@ namespace tracing {
 inline constexpr size_t kDefaultSharedMemorySizeBytes =
     4 * 1024 * 1024;  // 4 MB
 
-// TODO(crbug.com/40574593): Find a good compromise between performance and
-// data granularity (mainly relevant to running with small buffer sizes
-// when we use background tracing) on Android.
-#if BUILDFLAG(IS_ANDROID)
 inline constexpr size_t kDefaultSMBPageSizeBytes = 4 * 1024;
-#else
-inline constexpr size_t kDefaultSMBPageSizeBytes = 32 * 1024;
-#endif
 
 // Returns true if the system tracing Perfetto producer should be setup. This
 // can be influenced by the feature above or other situations (like debug