Roll ICU to 715ec351c0bcdd6b2d22f36e7d33b8e2ec519846 (#22380)

This change will make it easier to roll further changes into
Fuchsia.

Issue: https://github.com/flutter/flutter/issues/70007

DEPS

@@ -143,7 +143,7 @@ deps = {
    Var('chromium_git') + '/chromium/src/ios.git' + '@' + Var('ios_tools_revision'),
 
   'src/third_party/icu':
-   Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '146cb611fb2c1f53e63c2e59bd735d7a8ac6ec8c',
+   Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '715ec351c0bcdd6b2d22f36e7d33b8e2ec519846',
 
   'src/third_party/khronos':
    Var('chromium_git') + '/chromium/src/third_party/khronos.git' + '@' + '7122230e90547962e0f0c627f62eeed3c701f275',

ci/licenses_golden/licenses_third_party

-Signature: d9eae89a1e78eeab48c3f2091544cca5
+Signature: dce6528fb8a4a0af858039d641f0c6cc
 
 UNUSED LICENSES: