ci(macrobenchmark): Record why the benchmark runs on a high-end device

Older hardware would resolve SDK-init regressions better, but
Google_Pixel_4_13_real_us could not be allocated in three attempts -- each
queued ~61 minutes before Sauce gave up with a concurrency retry-timeout,
leaving an empty device log and tests="0". The Pixel 9 Pro XL allocates
reliably and is the device this pipeline is proven green on.

Author: runningcode

.sauce/sentry-uitest-android-macrobenchmark.yml

@@ -26,6 +26,14 @@ suites:
     # No test orchestrator and no clearPackageData: Macrobenchmark manages its own process
     # restarts and AOT compilation, and StartupMode.COLD intentionally keeps app data and
     # permissions (it force-stops rather than `pm clear`).
+    #
+    # Older hardware would give a better signal -- it spends longer in SentryAndroid.init, so a
+    # regression is larger against the same relative noise -- but Google_Pixel_4_13_real_us could
+    # not be allocated in three attempts, each queueing ~61 minutes before Sauce gave up with a
+    # concurrency retry-timeout. This device allocates reliably.
+    #
+    # Keep this to one device: two would produce two device logs, which the parser rejects rather
+    # than splice together -- see scripts/parse-macrobenchmark-log.py.
     devices:
       - id: Google_Pixel_9_Pro_XL_15_real_sjc1 # Google Pixel 9 Pro XL - api 35 (15) - high end