Roll ICU from d578f2e8b7bd to 8cc91d9b6ab9 (1 revision) (#191542)

https://chromium.googlesource.com/chromium/deps/icu.git/+log/d578f2e8b7bd..8cc91d9b6ab9

2026-08-12 manishearth@google.com [ICU] Exclude unused nfkc_scf.nrm from
ICU data bundle

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/icu-sdk-flutter
Please CC awolff@google.com,fuchsia-ui-discuss@google.com on the revert
to ensure that a human
is aware of the problem.

To file a bug in ICU: https://github.com/unicode-org/icu
To file a bug in Flutter:
https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md