GWP-ASan: Update field trials ProcessSampling param

These new process sampling parameters are now in use to cut GWP-ASan's
performance regression.

Bug: 896019, 912286
Change-Id: Ic45921cf307036a3896536fead041097169cf65c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1816369
Commit-Queue: Vlad Tsyrklevich <vtsyrklevich@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Auto-Submit: Vlad Tsyrklevich <vtsyrklevich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#700109}

testing/variations/fieldtrial_testing_config.json

@@ -2833,11 +2833,11 @@
                 {
                     "name": "Enabled",
                     "params": {
-                        "AllocationSamplingRange": "16",
-                        "MaxAllocations": "70",
-                        "MaxMetadata": "255",
+                        "AllocationSamplingRange": "64",
+                        "MaxAllocations": "35",
+                        "MaxMetadata": "150",
                         "ProcessSamplingBoost2": "10",
-                        "ProcessSamplingProbability": "0.05"
+                        "ProcessSamplingProbability": "0.01"
                     },
                     "enable_features": [
                         "GwpAsanMalloc",
@@ -2861,7 +2861,7 @@
                         "MaxAllocations": "70",
                         "MaxMetadata": "255",
                         "ProcessSamplingBoost2": "10",
-                        "ProcessSamplingProbability": "0.05"
+                        "ProcessSamplingProbability": "0.015"
                     },
                     "enable_features": [
                         "GwpAsanMalloc",