Migrate to agent based k8s integration

Description

This PR is to migrate k8s integration to agent based integration for deploying to k8s cluster. The task is to migrate whatever we have now as it is without adding additional functionality.

Related JIRA Issue(s)

https://www.ebi.ac.uk/panda/jira/browse/ENSWBSITES-2495

Review App URL(s)

None

Knowledge Base

Gitlab Agent : https://docs.gitlab.com/ee/user/clusters/agent/

YAML Anchors: https://docs.gitlab.com/ee/ci/yaml/yaml_optimization.html

Example(s)

Pipeline with example showing the dev context https://gitlab.ebi.ac.uk/ensembl-web/ensembl_search_hub/-/pipelines/504135

Dependencies

None