[chore][Weekly Report] Define required variable

[crobert-1]

Description: <Describe what has changed.>

Weekly report failure output:

ReferenceError: report is not defined
    at generateReport (/home/runner/work/opentelemetry-collector-contrib/opentelemetry-collector-contrib/.github/workflows/scripts/generate-weekly-report.js:243:3)
    at main (/home/runner/work/opentelemetry-collector-contrib/opentelemetry-collector-contrib/.github/workflows/scripts/generate-weekly-report.js:419:18)
    at async module.exports (/home/runner/work/opentelemetry-collector-contrib/opentelemetry-collector-contrib/.github/workflows/scripts/generate-weekly-report.js:425:3)
    at async eval (eval at callAsyncFunction (/home/runner/work/_actions/actions/github-script/v7/dist/index.js:35424:16), <anonymous>:4:1)
    at async main (/home/runner/work/_actions/actions/github-script/v7/dist/index.js:35[52](https://github.com/open-telemetry/opentelemetry-collector-contrib/actions/runs/9167350011/job/25204346835#step:4:53)2:20)
Error: Unhandled error: ReferenceError: report is not defined

I accidentally deleted a line I shouldn't have in https://github.com/open-telemetry/opentelemetry-collector-contrib/pull/32934, this re-adds the originally deleted line.