Add back issue generation for load test pipeline

[mowies]

Component(s)

testbed

Describe the issue you're reporting

#33885 removes the issue generation step from the load test pipeline, since it's outdated and therefore broken.

This should be added back in a working state. Maybe it can be switched out for an off-the-shelf github action.

[github-actions]

Pinging code owners:

• testbed: @open-telemetry/collector-approvers

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[mowies]

/label ci-cd