s3 pagination failures

[smallhive]

Closes #1175

The tests themselves need to be updated as well

[smallhive]

Change 1

This subpart of the test_s3_pagination_in_objects_versions_listing_via_boto3 fails each time, even without S3 gate communication

...
        with allure.step("Check pagination with starting token"):
            paginator = self.s3_client.get_paginator("list_object_versions")
    
            next_token = None
            all_versions = []
    
            while True:
                pagination_args = {"Bucket": bucket, "PaginationConfig": {"PageSize": 5}}
                if next_token:
                    pagination_args["PaginationConfig"]["StartingToken"] = next_token
    
                page_iterator = paginator.paginate(**pagination_args)
>               page = next(page_iterator)
E               TypeError: 'PageIterator' object is not an iterator

with error

FAILED pytest_tests/tests/s3/test_s3_versioning.py::TestS3Versioning::test_s3_pagination_in_objects_versions_listing_via_boto3[boto3] - TypeError: 'PageIterator' object is not an iterator

[smallhive]

Change 2

I consider that there is a logical error in the test_s3_pagination_in_objects_versions_listing_via_boto3 test.

We took max_keys (5 in the original code) and save it into versions. In the next subtest, we check these 5 items with a fully collected bucket, as a result 20 != 5.

We should update the test in the required way. Either change max_keys or get versions one more time on the next test

def test_s3_pagination_in_objects_versions_listing_via_boto3(self, prepare_versioned_objects: tuple):
        bucket, objects_count = prepare_versioned_objects
        with allure.step("Check basic pagination with MaxKeys"):
            max_keys = 5

to

def test_s3_pagination_in_objects_versions_listing_via_boto3(self, prepare_versioned_objects: tuple):
        bucket, objects_count = prepare_versioned_objects
        with allure.step("Check basic pagination with MaxKeys"):
            max_keys = objects_count

or another way, if the original assumption was different

[smallhive]

Change 3

inside test_s3_pagination_in_objects_versions_listing_via_cli

assert len(versions) == max_keys, f"Expected {max_keys} versions, got {len(versions)}"

replace with

assert len(versions) <= max_keys, f"Expected {max_keys} versions, got {len(versions)}"

The reason is here.
There are NeoFS search v2 cursor implementation-specific things against ListObjectVersions required behaviour

[evgeniiz321]

@smallhive
Change 1 - fixed
Change 2 - there was just a comparison with a wrong variable there - fixed it as well
Change 3 - fixed
But tests still fail on the original problem - The same next token was received twice from this PR as well

[roman-khimov]

@smallhive: all of the explanations belong to the commit message. That's exactly what it is for.

[smallhive]

Reworked

[roman-khimov]

Probably OK, we need more tests.