Update ICU

Rolling v8/third_party/icu: https://chromium.googlesource.com/chromium/deps/icu/+log/5fb93cb..85814e1

CP PR 2070 fix int32 overflow (Frank Tang)
https://chromium.googlesource.com/chromium/deps/icu/+/85814e1

CP two ICU security patches (Frank Tang)
https://chromium.googlesource.com/chromium/deps/icu/+/a47bd43

R=v8-waterfall-sheriff@grotations.appspotmail.com,mtv-sf-v8-sheriff@grotations.appspotmail.com,ftang@chromium.org

Change-Id: I2719b470184f94ad06b1920f0649628be3c93bf5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3615243
Bot-Commit: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#80289}

DEPS

@@ -226,7 +226,7 @@ deps = {
   'third_party/googletest/src':
     Var('chromium_url') + '/external/github.com/google/googletest.git' + '@' + 'af29db7ec28d6df1c7f0f745186884091e602e07',
   'third_party/icu':
-    Var('chromium_url') + '/chromium/deps/icu.git' + '@' + '5fb93cb43cfa9aa4063238f20e1e1a09aceade04',
+    Var('chromium_url') + '/chromium/deps/icu.git' + '@' + '85814e1af52482199a13d284545623ffbc9eef83',
   'third_party/instrumented_libraries':
     Var('chromium_url') + '/chromium/src/third_party/instrumented_libraries.git' + '@' + 'e09c4b66b6e87116eb190651421f1a6e2f3b9c52',
   'third_party/ittapi': {