rgw_sal_motr : [CORTX-32387] Fix null version-id issues in GET/HEAD object API

[priyanka25081999]

Problem Statement:
GET and HEAD object with null version-id does not contain "VersionId" field in the response

Solution:
In GET/HEAD object with --version-id null parameter for simple and multipart object, set the ent.key.instance value as null to show the VersionId field in the response.

Signed-off-by: Priyanka Salunke priyanka.s.salunke@seagate.com

Checklist

• Tracker (select at least one)
  • References tracker ticket
  • Very recent bug; references commit where it was introduced
  • New feature (ticket optional)
  • Doc update (no ticket needed)
  • Code cleanup (no ticket needed)
• Component impact
  • Affects Dashboard, opened tracker ticket
  • Affects Orchestrator, opened tracker ticket
  • No impact that needs to be tracked
• Documentation (select at least one)
  • Updates relevant documentation
  • No doc update is appropriate
• Tests (select at least one)
  • Includes unit test(s)
  • Includes integration test(s)
  • Includes bug reproducer
  • No tests

Show available Jenkins commands

• jenkins retest this please
• jenkins test classic perf
• jenkins test crimson perf
• jenkins test signed
• jenkins test make check
• jenkins test make check arm64
• jenkins test submodules
• jenkins test dashboard
• jenkins test dashboard cephadm
• jenkins test api
• jenkins test docs
• jenkins render docs
• jenkins test ceph-volume all
• jenkins test ceph-volume tox

[priyanka25081999]

• Tested the 1N k8s manual deployment - https://eos-jenkins.colo.seagate.com/job/Cortx-Automation/job/RGW/job/setup-cortx-rgw-cluster/10468/
• Sanity test - https://eos-jenkins.colo.seagate.com/job/Cortx-Automation/job/S3Server/job/S3-Compatibility-Test-Ceph-RGW/180/
• Added test logs in the JIRA - https://jts.seagate.com/secure/attachment/530320/530320_MGW+logs+-+CORTX-32387.txt