Remove indentation from XML responses

[alanking]

The response body returned by some operations includes newlines and indentation. Here is some example output from ListObjectsV2:

irods-client-s3-api-1  | [2026-03-02 21:06:06.450] [P:1] [debug] [T:14] handle_listobjects_v2: response body <?xml version="1.0" encoding="utf-8"?>
irods-client-s3-api-1  | <ListBucketResult>
irods-client-s3-api-1  |     <Name>/tempZone/home/public</Name>
irods-client-s3-api-1  |     <Prefix/>
irods-client-s3-api-1  |     <Marker/>
irods-client-s3-api-1  |     <IsTruncated>false</IsTruncated>
irods-client-s3-api-1  |     <Contents>
irods-client-s3-api-1  |         <Key>PowerShell_transcript.ALANKING-WINDEV.PAM%2BNjaF.20260209132144.txt</Key>
irods-client-s3-api-1  |         <ETag>/tempZone/home/publicPowerShell_transcript.ALANKING-WINDEV.PAM+NjaF.20260209132144.txt</ETag>
irods-client-s3-api-1  |         <Owner>rods</Owner>
irods-client-s3-api-1  |         <Size>1018</Size>
irods-client-s3-api-1  |         <LastModified>2026-03-02T17:53:30.000Z</LastModified>
irods-client-s3-api-1  |     </Contents>
irods-client-s3-api-1  | </ListBucketResult>

While this is nice for debugging and human readability, we should get rid of the indentation to reduce response sizes.

Here are the relevant lines for ListObjectsV2:

irods_client_s3_api/endpoints/s3/src/listobjects.cpp

Lines 264 to 265 in 49f41c2

	settings.indent_char = ' ';
	settings.indent_count = 4;