RTECO-235 - Refactoring code

[naveenku-jfrog]

Problem Statement: Code is complex for handling repoOnly change

Solution:

1. Removed the logic for running for setting properties for repo only on separate thread, as we know that only API request will be there, so no need to do overcomplex things.
2. Also reduced complexity in performRequest function which is for handling for artifacts.

Related PRs: jfrog/jfrog-cli-artifactory#103

• All tests passed. If this feature is not already covered by the tests, I added new tests.
• All static analysis checks passed.
• This pull request is on the dev branch.
• I used gofmt for formatting the code before submitting the pull request.

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