[CI] Pending loads-test tasks

[sincejune]

Component(s)

No response

Describe the issue you're reporting

Description

loads-test is pending on waiting self-hosted machines for hours.

ref: https://github.com/open-telemetry/opentelemetry-collector-contrib/actions/workflows/load-tests.yml?query=branch%3Amain

[songy23]

This is expected because this repo has many commits on mainline, and the load test tasks are just queuing.

My question to @open-telemetry/collector-contrib-approvers is: do we really need to run load tests on every commit on mainline? Seems a bit overkill to me.

[atoulme]

At least once a day would be great for trend building.

[sincejune]

Raised #38483 for adding a manual trigger and a scheduled trigger (also removing the existing push trigger) cc @songy23 @atoulme