Currently, the icu::Locale::canonicalize process will consider the information in the REDUNDANT array so
for example "sgn-GR" will be canonicalized into "gss" .
Bug https://unicode-org.atlassian.net/browse/ICU-21115 mentioned several cases and ICU-TC advise me to file bug against CLDR.
So I filed https://unicode-org.atlassian.net/browse/CLDR-13809 but CLDR-TC decide not to add sgn-* to the file.
So we should remove them from REDUNDANT. Otherwise, icu::Locale::canonicalize won't be consist with UTS35 because the Locale constructor will change sgn-GR into gss.