CiaB: Use rpm command instead of yum to avoid fetching repo metadata that will go unused

[zrhoffman]

What does this PR (Pull Request) do?

This PR changes CDN-in-a-Box to install the ATC components directly using rpm instead of through yum, which makes syncing yum repos unnecessary if the RPM installation layers are the only ones needing to be rebuilt. This can save several minutes building CDN-in-a-Box, depending on your Internet speed.

• This PR is not related to any Issue

Which Traffic Control components are affected by this PR?

• CDN in a Box

What is the best way to verify this PR?

• Ensure CDN-in-a-Box builds successfully and that the readiness container exits successfully

The following criteria are ALL met by this PR

• CDN-in-a-Box change, no tests necessary
• Behavior unchanged, no additional documentation necessary
• An update to CHANGELOG.md is not necessary
• This PR includes any and all required license headers
• This PR ensures that database migration sequence is correct OR this PR does not include a database migration
• This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY (see the Apache Software Foundation's security guidelines for details)

[ocket8888]

Builds fine, CiaB readiness container exits