Increase execution_timeout for ci/win-arm64-rel

The builder regularly hitting 4hr timeout for long build time. This CL
increased the execution_timeout to 5hr.

Bug: 417984353
Change-Id: Id76856c2e0318438b403d40d3f35d2337e71dd21
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6554363
Reviewed-by: Garrett Beaty <gbeaty@google.com>
Commit-Queue: Kuan Huang <kuanhuang@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1461031}

infra/config/generated/luci/cr-buildbucket.cfg

@@ -69491,7 +69491,7 @@ buckets {
         '    "chromium"'
         '  ]'
         '}'
-      execution_timeout_secs: 14400
+      execution_timeout_secs: 18000
       build_numbers: YES
       service_account: "chromium-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
       experiments {

infra/config/subprojects/chromium/ci/chromium.win.star

@@ -668,9 +668,9 @@ ci.builder(
     ),
     cq_mirrors_console_view = "mirrors",
     contact_team_email = "chrome-desktop-engprod@google.com",
-    # Can flakily hit the default 3 hour timeout due to inconsistent compile
-    # times.
-    execution_timeout = 4 * time.hour,
+    # 20min (bot update) + 3hr (compile time without cache) +
+    # 40min (isolate tests) with 1hr buffer
+    execution_timeout = 5 * time.hour,
     # Increase timeout for connecting to dependency scanner
     reclient_bootstrap_env = {
         "RBE_depsscan_connect_timeout": "120s",