Fix json mapping and copying proto optionals in SQS Json API.

[siarheivesialou]

Fix incorrect conversion from json object to protobuf map in http_proxy.
Fix incorrect copying of optional fields from old proto to new proto in SQS Json API.

[github-actions]

⚪ 2024-09-02 09:19:30 UTC Pre-commit check for 3020dab has started.
⚪ 2024-09-02 09:22:15 UTC Build linux-x86_64-release-clang14 is running...
🟢 2024-09-02 09:29:58 UTC Build successful.

[github-actions]

⚪ 2024-09-02 09:20:02 UTC Pre-commit check for 3020dab has started.
⚪ 2024-09-02 09:22:42 UTC Build linux-x86_64-release-asan is running...
🟢 2024-09-02 09:47:51 UTC Build successful.
⚪ 2024-09-02 09:48:07 UTC Tests are running...
🔴 2024-09-02 11:52:05 UTC Some tests failed, follow the links below.

Test history | Test log

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
15554	15444	0	29	50	31

🟢 2024-09-02 11:52:50 UTC ydbd size 5.5 GiB changed* by +52.2 KiB, which is < 100.0 KiB vs stable-24-3-6-logbroker: OK

ydbd size dash	stable-24-3-6-logbroker: 0718e63	merge: 3020dab	diff	diff %
ydbd size	5 931 255 376 Bytes	5 931 308 848 Bytes	+52.2 KiB	+0.001%
ydbd stripped size	1 487 234 656 Bytes	1 487 258 432 Bytes	+23.2 KiB	+0.002%

^{*please be aware that the difference is based on comparing your commit and the last completed build from the post-commit, check comparation}

[github-actions]

⚪ 2024-09-02 09:22:03 UTC Pre-commit check for 3020dab has started.
⚪ 2024-09-02 09:24:55 UTC Build linux-x86_64-relwithdebinfo is running...
🟢 2024-09-02 10:07:58 UTC Build successful.
⚪ 2024-09-02 10:10:45 UTC Tests are running...
🔴 2024-09-02 12:32:49 UTC Some tests failed, follow the links below.

Test history | Test log

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
76625	63166	0	2	13427	30

🟡 2024-09-02 12:33:31 UTC ydbd size 8.2 GiB changed* by +140.7 KiB, which is >= 100.0 KiB vs stable-24-3-6-logbroker: Warning

ydbd size dash	stable-24-3-6-logbroker: 0718e63	merge: 3020dab	diff	diff %
ydbd size	8 756 604 296 Bytes	8 756 748 352 Bytes	+140.7 KiB	+0.002%
ydbd stripped size	478 801 000 Bytes	478 808 264 Bytes	+7.1 KiB	+0.002%

^{*please be aware that the difference is based on comparing your commit and the last completed build from the post-commit, check comparation}