sp: fix missing key names when query contains GROUP BY

[koleini]

Key names are missing from the output record for the keys inside GROUP BY statement.

Fixes #7459

Enter [N/A] in the box, if an item is not applicable to your change.

Testing
Before we can approve your change; please submit the following in a comment:

• [N/A] Example configuration file for the change
• [] Debug log output from testing the change

• Attached Valgrind output that shows no leaks or memory corruption was found

# valgrind --leak-check=full ./bin/fluent-bit -c ../conf/bug
==98401== Memcheck, a memory error detector
==98401== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==98401== Using Valgrind-3.18.1 and LibVEX; rerun with -h for copyright info
==98401== Command: ./bin/fluent-bit -c ../conf/bug
==98401== 
Fluent Bit v2.2.0
* Copyright (C) 2015-2022 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

[2023/10/12 03:39:28] [ info] [fluent bit] version=2.2.0, commit=da569ea7d0, pid=98401
[2023/10/12 03:39:28] [ info] [storage] ver=1.5.1, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2023/10/12 03:39:28] [ info] [cmetrics] version=0.6.3
[2023/10/12 03:39:28] [ info] [output:stdout:stdout.0] worker #0 started
[2023/10/12 03:39:28] [ info] [ctraces ] version=0.3.1
[2023/10/12 03:39:28] [ info] [input:tail:tail.0] initializing
[2023/10/12 03:39:28] [ info] [input:tail:tail.0] storage_strategy='memory' (memory only)
[2023/10/12 03:39:28] [ info] [input:stream_processor:agg.logs] initializing
[2023/10/12 03:39:28] [ info] [input:stream_processor:agg.logs] storage_strategy=(null)
[2023/10/12 03:39:28] [ info] [sp] stream processor started
[2023/10/12 03:39:28] [ info] [sp] registered task: agg_stream
[2023/10/12 03:39:28] [ info] [input:tail:tail.0] inotify_fs_add(): inode=3547685 watch_fd=1 name=/var/log/bug
[0] logs.acc: [[1697081971.254292876, {}], {"server"=>"stage01", "host"=>"host1.com", "size_sent"=>"1", "body_size"=>"9"}]
[1] logs.acc: [[1697081971.747697882, {}], {"server"=>"stage01", "host"=>"host1.com", "size_sent"=>"1", "body_size"=>"8"}]
[0] logs.acc: [[1697081972.251094097, {}], {"server"=>"stage01", "host"=>"host1.com", "size_sent"=>"1", "body_size"=>"7"}]
[0] agg.logs: [[1697081971.902873596, {}], {"server"=>"stage01", "host"=>"host1.com", "SUM(size_sent)"=>2}]
[0] agg.logs: [[1697081972.906615055, {}], {"server"=>"stage01", "host"=>"host1.com", "SUM(size_sent)"=>1}]
^C[2023/10/12 03:39:40] [engine] caught signal (SIGINT)
[2023/10/12 03:39:40] [ warn] [engine] service will shutdown in max 5 seconds
[2023/10/12 03:39:40] [ info] [input] pausing tail.0
[2023/10/12 03:39:40] [ info] [input] pausing agg.logs
[2023/10/12 03:39:40] [ info] [engine] service has stopped (0 pending tasks)
[2023/10/12 03:39:40] [ info] [input] pausing tail.0
[2023/10/12 03:39:40] [ info] [input] pausing agg.logs
[2023/10/12 03:39:40] [ info] [output:stdout:stdout.0] thread worker #0 stopping...
==98401== 
==98401== HEAP SUMMARY:
==98401==     in use at exit: 0 bytes in 0 blocks
==98401==   total heap usage: 5,091 allocs, 5,091 frees, 2,695,507 bytes allocated
==98401== 
==98401== All heap blocks were freed -- no leaks are possible
==98401== 
==98401== For lists of detected and suppressed errors, rerun with: -s
==98401== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

If this is a change to packaging of containers or native binaries then please confirm it works for all targets.

• [N/A] Run local packaging test showing all targets (including any new ones) build.
• [N/A] Set ok-package-test label to test for all targets (requires maintainer to do).

Documentation

• [N/A] Documentation required for this feature

Backporting

• [N/A] Backport to latest stable release.

---

Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

[edsiper]

@koleini welcome back!

please sign off your commits here to avoid the DCO error from github. thank you