Fix CacheStorageParallelOps fieldtrial testing config.

Bug: 985379
Change-Id: I97fec3bf531e32ea8c8fc30693db59f22dee7a5c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1746767Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Ben Kelly <wanderview@chromium.org>
Cr-Commit-Position: refs/heads/master@{#686174}

testing/variations/fieldtrial_testing_config.json

@@ -1424,7 +1424,7 @@
                 {
                     "name": "Enabled16_v1",
                     "params": {
-                        "max_shares_ops": "16"
+                        "max_shared_ops": "16"
                     },
                     "enable_features": [
                         "CacheStorageParallelOps"