Deprecate the 'Send Reassure Performance Tests to Graphite' GitHub Actions workflow

[mountiny]

Overview

The Send Reassure Performance Tests to Graphite workflow (defined in .github/workflows/sendReassurePerfData.yml) runs on every push to main and ships Reassure performance numbers to stats.expensify.com:3003 via netcat for ingestion into Graphite.

This workflow is no longer needed:

• We already run Reassure on every PR via .github/workflows/reassurePerformanceTests.yml, which is what actually gates performance regressions during review.
• The Graphite dashboards fed by this job are not actively used to make decisions, and the post-merge numbers produced here are not tied to any ownership or alerting.
• The workflow consumes a Blacksmith runner on every single merge to main (running hundreds of times a week — see the workflow run history), which is a meaningful and ongoing CI cost for no tangible benefit.

Proposal

Remove the workflow and the Action it depends on, since it is only referenced by this workflow:

• Delete .github/workflows/sendReassurePerfData.yml.
• Delete .github/actions/javascript/getGraphiteString/ (including action.yml, getGraphiteString.ts, and the compiled index.js).
• Remove the getGraphiteString entry from .github/scripts/buildActions.sh.

No production code or developer-facing tooling is affected. PR-level performance checks continue to run through reassurePerformanceTests.yml.