Fix BDN scaling issue so that each framework is saved to different branch

[darrenge]

Due to scalability issues with the BDN (run into contention when pushing so much chart data to the same branch \ file), we will break the data location to separate branch for 8.0 (continuousbenchmark_net80) and continue to use existing continuousbenchmark branch as the "latest".

Also includes changes to deploy-website.yml where it copies over as data.js (from 80 branch) to data_net8.0.js

We will NOT push this PR until the html file for the chart (index.html) and data files on continuousbenchmark branch are updated .

[Copilot]

Pull Request Overview

This PR fixes the BDN scaling issue by separating the storage of chart data into two distinct branches—one for the net8.0 framework and another for the latest continuous benchmark. Key changes include:

• Adding a new checkout step in deploy-website.yml to retrieve chart data from the continuousbenchmark_net80 branch.
• Modifying the file copy procedure in deploy-website.yml to copy data.js as data_net80.js for the net8.0 branch.
• Updating ci-bdnbenchmark.yml to dynamically choose the GitHub pages branch based on the framework using a conditional expression.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
.github/workflows/deploy-website.yml	Added checkout and copy steps for the continuousbenchmark_net80 branch.
.github/workflows/ci-bdnbenchmark.yml	Updated the gh-pages-branch expression to select between net8.0 and the default branch.