[benchmarking] increase the shard count for mac high end back to 26

The shard count was reduced to 23 due to uncertainty of lab workforce at the beginning of COVID-19. Now we can bring it back to 26.

Bug: chromium:1068120
Change-Id: If492e78863f64579a18b01a14c53197dfd018ab0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2422251
Auto-Submit: Wenbin Zhang <wenbinzhang@google.com>
Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809066}

testing/buildbot/chromium.perf.json

@@ -1119,7 +1119,7 @@
           "ignore_task_failure": false,
           "io_timeout": 21600,
           "service_account": "chrome-tester@chops-service-accounts.iam.gserviceaccount.com",
-          "shards": 23
+          "shards": 26
         },
         "trigger_script": {
           "args": [

tools/perf/core/bot_platforms.py

@@ -426,10 +426,7 @@ MAC_HIGH_END = PerfPlatform(
     'mac-10_13_laptop_high_end-perf',
     'MacBook Pro, Core i7 2.8 GHz, 16GB RAM, 256GB SSD, Radeon 55',
     _MAC_HIGH_END_BENCHMARK_CONFIGS,
-    # crbug.com/1068120
-    # The shard size is reduced from 26 to 23 due to the COVID-19
-    # situation that labs may not be able to recover devices in time.
-    23,
+    26,
     'mac',
     executables=_MAC_HIGH_END_EXECUTABLE_CONFIGS)
 MAC_LOW_END = PerfPlatform(