[OSS] Add gatsby-build-newrelic plugin to OSS site

[jpvajda]

Related Bug: https://github.com/newrelic-experimental/gatsby-build-newrelic/issues/24

Following the instructions here, add the gatsby-build-newrelic plugin to the OSS site an install the quckstart for gatsby build for so we can measure the OSS sites build times more effectively.

Acceptance Criteria

• [x] Update Gatsby config to use gatsby build new relic
• [x] test on gatsby site for the PR branch
• [x] Setup up Env variables required for Gatsby build new relic on opensource develop site on Gatsby cloud
• [x] Setup up Env variables required for Gatsby build new relic on opensource main site on Gatsby cloud
• [x] merge changes to develop branch
• [x] merge develop to main
• [x] install quickstart for gastby build on our developer enablement account
• [x] delete opensource-website-gatsby-build-newrelic in Gatsby Cloud (as it was for testing)
• [x] delete test dashboard for opensource-website-gatsby-build-newrelic in New Relic
• [x] look at some sweet dashboards

[jpvajda]

This ticket lead to some documentation updates in the plugin repo which @rudouglas did, and we found a bug: newrelic-experimental/gatsby-build-newrelic#24.

question: @rudouglas should we resolve this bug before I put this change on the develop branch? It seems it's just impacted the metrics dashboards, but I wanted to check before I proceed.

[rudouglas]

Ye lets hold off until we can get the metrics reporting @jpvajda

[rudouglas]

This is fixed now @jpvajda just remember we need the Environment variables in develop and main if we're going to merge the PR

[jpvajda]

@rudouglas you just made my list of ACs 🤣

[jpvajda]

Re-opening as the merge from develop to main failed a check

https://github.com/newrelic/opensource-website/pull/888

[jpvajda]

dashboard can be found here.