cleanup(Windows): remove $PushVersion blocks from make.ps1

[lemeurherve]

This PR removes unused block codes related to $PushVersion.

Only existing mention of $PushVersion in this repo:

• Add docker baking #1137 (comment)

Similar to:

• cleanup(Windows): remove obsolete PushVersion build.ps1 script argument docker-agent#548

Note: I intend to refactor make.ps1 to be similar to the build.ps1 of https://github.com/jenkinsci/docker-agent and https://github.com/jenkinsci/docker-inbound-agent, this cleanup will facilitate the comparison between both scripts.

Testing done

Removal of uncalled code, CI should suffice.

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