start using `write_body` in `rest/client` to properly set headers due to changes applied to seastar's http client
Seastar module update
```
b6be384e Merge 'http: generalize Content-Type setting' from Nadav Har'El
74472298 http: generalize request's Content-Type setting
9fd5a1cc http: generalize reply's Content-Type setting
a2665f38 memory: Remove deprecated enable_abort_on_allocation_failure()
d2a5a8a9 resource.cc: Remove some dead code
7ad9f424 http: Add support of multiple key repetitions for the request
a636baca task: Move task::get_backtrace() definition in its class
a0101efa Fixed "doxygen" spelling in error message
db969482 Merge 'http/reply: introduce set_cookie()' from Botond Dénes
5357b434 http/reply: introduce set_cookie()
1ddcf05f http/reply: make write_reply*() public
4b782d73 http/connection: start_response(): fix indentation
720feca0 http/reply: encapsulate reply writing in write_reply()
3e19917d Merge 'exceptions: log thrown and propagated exception with distinct log levels' from Botond Dénes
db9aea93 Merge 'Correctly wrap up abandoned yielding directory lister' from Pavel Emelyanov
dbb2bf3f test: Add test for input_stream::read_exactly()
a5308ec9 file/directory_lister: Correctly wrap up fallback generator
4f0811f4 file/directory_lister: Convert on-stack queue to shared pointer
59801da7 tests: Add directory lister early drop cases
33233032 http/reply: s/write_reply_to_connection/write_reply/
69b93620 http/reply: write_reply_{to_connection,headers}(): pass output stream
56e9bda7 test: Convert directory_test into seastar test
96782358 Merge 'Improve io_tester's seqwrite and append workloads' from Pavel Emelyanov
8b46e3d4 SEASTAR_ASSERT: assert to stderr and flush stream
3370e22a tutorial.md: use current_exception_as_future()
e977453a Add fixture support for seastar::testing
3e70d7f7 io_tester: Do not set append_is_unlikely unconditionally
2a4ae7b4 io_tester: Count file size overflows
5e678bb5 io_tester: Tuneup size overflow check
d5dad8ce io_tester: Move position management code to io_class_data
5586a056 io_tester: Rename seqwrite -> overwrite
92df2fb2 io_tester: Relax return value of create_and_fill_file()
03d9500d io_tester: Dont fill file for APPEND
d6844a7b io_tester: Indentation fix after previous patch
fb9e0088 io_tester: Coroutinize create_and_fill_file()
2f802f57 exceptions: log thrown and propagated exception with distinct log levels
4971fa70 util: move log-level into own header
39448fc1 Merge 'Fix and tune http::request setup by client' from Pavel Emelyanov
52d0c4fb iostream: Move output_stream::write(scattered_message) lower
7a52f734 Merge 'read_first_line: Missing pragma and licence' from Ernest Zaslavsky
d0881b7e read_first_line: Add missing license boilerplate
988a0e99 read_first_line:: Add missing `#pragma once`
42675266 http: Make client::make_request accept const request&
c7709fb5 http: Make request making API return exceptional future not throw
b68ed89b http: Move request content length header setup
1d96dac6 http: Move request version configuration
072e86f6 http: Setup request once
```
Closesscylladb/scylladb#25915
(cherry picked from commit 44d34663bc)
Closesscylladb/scylladb#26100
e56081d588