chore(pipeline): use infra.getBuildAgentLabel in agentSelector

[lemeurherve]

This change delegates the choice of labels depending on the platform and the controller where the build is running from to infra.getBuildAgentLabel.

Similar to:

• chore(pipeline): use infra.getBuildAgentLabel in agentSelector docker-agents#1137

Refs:

• feat(infra.getBuildAgentLabel): add docker jobs labels jenkins-infra/pipeline-library#980

Testing done

CI

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