Quota: Update fieldtrial testing config with new suffix.

This experiment is going to move into stable and in doing so, the suffix needed to be updated on Finch's end, so in order to have the presubmit bots pass, this config must be updated to match.

Bug: 919693
Change-Id: I2122ee0deb3810253388ceefeda2dc530bb273ac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1593548Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Jarryd Goodman <jarrydg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#657325}

testing/variations/fieldtrial_testing_config.json

@@ -4060,7 +4060,7 @@
             ],
             "experiments": [
                 {
-                    "name": "Enabled_Pool_Four_Fifths_Origin_ThreeQuarters_20190307",
+                    "name": "Enabled_Pool_Four_Fifths_Origin_ThreeQuarters_20190430",
                     "params": {
                         "PerHostRatio": "0.75",
                         "PoolSizeRatio": "0.8"