[Perf] Update android-pixel4a_power-perf device_os

The android-pixel4a_power-perf devices have been upgraded to
Android R.

Bug: 1151960
Change-Id: I6ce779c97d8f8ee39ab5826800bdf914e5b782ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2566493
Auto-Submit: John Chen <johnchen@chromium.org>
Reviewed-by: Wenbin Zhang <wenbinzhang@google.com>
Commit-Queue: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832400}

testing/buildbot/chromium.perf.json

@@ -674,7 +674,7 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "device_os": "QD4A.200102.001.A1",
+              "device_os": "RQ1D.201205.012",
               "device_os_flavor": "google",
               "device_type": "sunfish",
               "os": "Android",

tools/perf/core/perf_data_generator.py

@@ -538,7 +538,7 @@ BUILDERS = {
             'pool': 'chrome.tests.pinpoint',  # Sharing Pinpoint pool
             'os': 'Android',
             'device_type': 'sunfish',
-            'device_os': 'QD4A.200102.001.A1',
+            'device_os': 'RQ1D.201205.012',
             'device_os_flavor': 'google',
         },
     },