[CP-stable] Upgrade dependency on package:unified_analytics from 5.8.8+1 to 5.8.8+2 (flutter#151046)

Resolves flutter#150137 (the issue is already resolved in master with the use of package:unified_analytics:6.1.2).

Patches the fixes from [unified_analytics:5.8.8+2](dart-lang/tools#280) to stable.

Author: andrewkolos

packages/flutter_tools/pubspec.yaml

@@ -52,7 +52,7 @@ dependencies:
   http_multi_server: 3.2.1
   convert: 3.1.1
   async: 2.11.0
-  unified_analytics: 5.8.8+1
+  unified_analytics: 5.8.8+2
 
   cli_config: 0.2.0
   graphs: 2.3.1
@@ -120,4 +120,4 @@ dartdoc:
   # Exclude this package from the hosted API docs.
   nodoc: true
 
-# PUBSPEC CHECKSUM: 067f
+# PUBSPEC CHECKSUM: d480