Update config.props to 17.14 Preview 1

[donnie-msft]

Related: https://github.com/NuGet/Client.Engineering/issues/3128
Update branding in dev branch to 6.14.0-preview.1

[nkolev92]

Not necessarily a blocker for this PR since I merged my change, but I'd like to get c4b2619 in as well in the insertion tomorrow.

Please use the branching template, since there's quite a bit to be done beyond just changing the branding: https://github.com/NuGet/Client.Engineering/issues/new?assignees=&labels=Type%3AEngineering%2CPriority%3A2&projects=&template=branch_template.md

[nkolev92]

The branching template is supposed to be an issue.

Within it, there's changes that require more than 1 PR (changes to both release and dev branches)

[donnie-msft]

The branching template is supposed to be an issue.

@nkolev92 sounds good, I have put this PR back how it was originally and created https://github.com/NuGet/Client.Engineering/issues/3128.

Within it, there's changes that require more than 1 PR (changes to both release and dev branches)

There are multiple PRs I created and linked in that issue. I'm only waiting on them being merged so I can progress through the rest of the checklist.