Set GitHub Action Workflow token to the least privileged level

Currently, the GitHub token associated with apache/nifi workflows are elevated. Here is an example of elevated GitHub token:

https://github.com/apache/nifi/actions/runs/3167551611/jobs/5158128990#step:1:19

The token permissions should be adjusted to include only the required permissions.

Motivation and Context

• This is a security best practice, so if the GITHUB_TOKEN is compromised due to a vulnerability or compromised Action, the damage will be reduced.
• GitHub recommends defining minimum GITHUB_TOKEN permissions.
• The Open Source Security Foundation (OpenSSF) Scorecards also treats not setting token permissions as a high-risk issue. This change will help increase the Scorecard score for this repository