luci: raise cros asan builder timeout to 6h.

Timing out frequently, possibly due to crrev.com/c/2125464

Change-Id: Iee1d7d9965bdb2858930d40d6f9d0fb56f99aabc
Bug: 1066570
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2129999Reviewed-by: Ben Pastene <bpastene@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#755061}

infra/config/buckets/ci.star

@@ -1657,7 +1657,7 @@ ci.memory_builder(
     name = 'Linux Chromium OS ASan LSan Builder',
     # TODO(crbug.com/1030593): Builds take more than 3 hours sometimes. Remove
     # once the builds are faster.
-    execution_timeout = 4 * time.hour,
+    execution_timeout = 6 * time.hour,
 )
 
 ci.memory_builder(

infra/config/generated/cr-buildbucket.cfg

@@ -2637,7 +2637,7 @@ buckets: <
         properties_j: "$kitchen:{\"devshell\":true,\"git_auth\":true}"
         properties_j: "mastername:\"chromium.memory\""
       >
-      execution_timeout_secs: 14400
+      execution_timeout_secs: 21600
       build_numbers: YES
       service_account: "chromium-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
     >