Add find_timeouts and caching to tools/gardening

tools/gardening/bin/create_shard_groups.dart

Index: tools/gardening/bin/create_shard_groups.dart
diff --git a/tools/gardening/bin/create_shard_groups.dart b/tools/gardening/bin/create_shard_groups.dart
index 4a690e65258bf113ff4640af74e343ed7e9ccdc9..0a2f7eb571c23c44f9a9a73e728ea41a437e4c9b 100644
--- a/tools/gardening/bin/create_shard_groups.dart
+++ b/tools/gardening/bin/create_shard_groups.dart
@@ -14,7 +14,7 @@ const String groupsEndMark = r"<tr class='DevStatusSpacing'>";
 List<String> findGroups(List<String> source) {
   List<String> result = <String>[];
   bool started = false;
-  
+
   for (String line in source) {
     if (line.contains(groupsStartMark)) started = true;
     if (started) {
@@ -51,8 +51,8 @@ List<List<String>> findShards(List<String> source) {
         int quoteIndex = trimmed.indexOf("'", buildersIndex);
         if (quoteIndex >= 0) {
           // Found a shard name, add it.
-          shardResult.add(trimmed.substring(
-              buildersIndex + shardMark.length, quoteIndex));
+          shardResult.add(
+              trimmed.substring(buildersIndex + shardMark.length, quoteIndex));
         } else {
           // Unexpected source formatting, skip.
         }
@@ -63,7 +63,7 @@ List<List<String>> findShards(List<String> source) {
       }
     }
   }
-  return result;  
+  return result;
 }
 
 main(List<String> args) {