[AM] Increase allowable paramset length to 1MB from 1000B.

Change-Id: I368adc52e113cabf98dbee916114345abeb57bce
Bug: skia:8385
Reviewed-on: https://skia-review.googlesource.com/c/178868
Commit-Queue: Ravi Mistry <rmistry@google.com>
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
diff --git a/am/go/silence/silence.go b/am/go/silence/silence.go
index 8747bb2..ee1fdea 100644
--- a/am/go/silence/silence.go
+++ b/am/go/silence/silence.go
@@ -26,7 +26,7 @@
 	Active         bool                `json:"active" datastore:"active"`
 	User           string              `json:"user" datastore:"user"`
 	ParamSet       paramtools.ParamSet `json:"param_set" datastore:"-"`
-	ParamSetSerial string              `json:"-" datastore:"param_set_serial"`
+	ParamSetSerial string              `json:"-" datastore:"param_set_serial,noindex"`
 	Created        int64               `json:"created" datastore:"created"`
 	Updated        int64               `json:"updated" datastore:"updated"`
 	Duration       string              `json:"duration" datastore:"duration"`