OSSM 2.1.1 Refactor maistra-test-tool using Golang text template

This is a sub task of OSSM-821 and a follow up of
https://github.com/maistra/maistra-test-tool/pull/264

Need to investigate the coding pattern of Golang text template for yaml content templating.
Need to avoid using hard-coded SMCP name and namespace.
Need to refactor the current maistra 2.1 test scripts.
Need to collaborate with IBM engineer for a PR review and test automation changes before merging it from a working branch into a maistra-2.1 testing branch.