date_format() UDF is returning output in UTC time zone only

HIVE - 1.2

sshuser@hn0-dateti:~$ timedatectl

Local time: Thu 2021-05-06 11:56:08 IST
Universal time: Thu 2021-05-06 06:26:08 UTC
RTC time: Thu 2021-05-06 06:26:08
Time zone: Asia/Kolkata (IST, +0530)
Network time on: yes
NTP synchronized: yes
RTC in local TZ: no

sshuser@hn0-dateti:~$ beeline
0: jdbc:hive2://localhost:10001/default> select date_format(current_timestamp,"yyyy-MM-dd HH:mm:ss.SSS z");
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1 row selected (1.271 seconds)

HIVE - 3.1.0

sshuser@hn0-testja:~$ timedatectl
Local time: Thu 2021-05-06 12:03:32 IST
Universal time: Thu 2021-05-06 06:33:32 UTC
RTC time: Thu 2021-05-06 06:33:32
Time zone: Asia/Kolkata (IST, +0530)
Network time on: yes
NTP synchronized: yes
RTC in local TZ: no

sshuser@hn0-testja:~$ beeline
0: jdbc:hive2://zk0-testja.e0mrrixnyxde5h1suy> select date_format(current_timestamp,"yyyy-MM-dd HH:mm:ss.SSS z");
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1 row selected (13.396 seconds)

0: jdbc:hive2://zk0-testja.e0mrrixnyxde5h1suy> set hive.local.time.zone=Asia/Kolkata;
No rows affected (0.025 seconds)
0: jdbc:hive2://zk0-testja.e0mrrixnyxde5h1suy> select date_format(current_timestamp,"yyyy-MM-dd HH:mm:ss.SSS z");
------------------------------

------------------------------

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1 row selected (1.074 seconds)

expected result was 2021-05-06 12:08:15.118 IST

As part of HIVE-12192 it was decided to have a common time zone for all computation i.e. "UTC". Due to which data_format() function was hard coded to "UTC".

But later in HIVE-21039 it was decided that user session time zone value should be the default not UTC.

date_format() was not fixed as part of HIVE-21039.

what should be the ideal time zone value of date_format().