Describe the bug
When working with the cyrillic based texts, I noticed that the word prefix queries does not search any records for me. Another issue, a provided search term must be case-sensitive. On the other hand, word suffix works well but it is case-sensitive too.

To Reproduce
Setup a hash:

hset test:1 Ref "09add9ee-2544-11ee-a361-48df37b92096" Description "Абрикосове"
hset test:2 Ref "1b009444-4e4a-11ed-a361-48df37b92096" Description "Абранка"
hset test:3 Ref "6dbe932e-1aad-11ea-8c15-0025b502a06e" Description "Абрикосівка"

Create an index:

ft.create idx on hash prefix 1 test: schema Ref as ref tag Description as desc text

Try to search records with word prefixes:

FT.SEARCH idx "@desc:Абр*"
FT.SEARCH idx "@desc:Абрикос*"

Case-insensitive search is also does not give any result:

FT.SEARCH idx "@desc:абранка"

All above commands are ended with No results found. message.
Only a full case-sensitive search is working: FT.SEARCH idx "@desc:Абранка".

Expected behavior
Found the records with word prefix and case-insensitive search.

Environment (please complete the following information):

• redis/redis-stack:latest (7.2.5) docker image
• redis search: 2.8.14