Update function parseRepoBranch()

Originally the function parseRepoBranch() consume strings `octocat/aqa-tests:test` and return the repo `octocat/aqa-tests` and branch 'test'.
User will use the return `repoBranch` to generate the git url like `--tkg_branch ${repoBranch[1]} --tkg_repo https://github.com/${repoBranch[0]}.git`.

We'd like to enhance the parseRepoBranch() to include the git url generation logic.

Start by locating parseRepoBranch() and inspecting its callers to understand the current repo-and-branch return shape. Check for tests covering parsing or git argument construction; done means the function supports the requested git URL generation while preserving the expected branch value and callers remain correct.

Written by the indexing model from the issue text.