Update BlobDataPipeTuning fieldtrial testing config.

Bug: 1010199
Change-Id: I27237b3f1bc586626646a9c1c8712bcfa4a558c2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1845857Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Ben Kelly <wanderview@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704322}

testing/variations/fieldtrial_testing_config.json

@@ -1394,10 +1394,9 @@
             ],
             "experiments": [
                 {
-                    "name": "Capacity_512kb_Chunk_64kb",
+                    "name": "Enabled_2MB_v1",
                     "params": {
-                        "capacity_bytes": "524288",
-                        "chunk_bytes": "65536"
+                        "capacity_bytes": "2097152"
                     },
                     "enable_features": [
                         "BlobDataPipeTuning"