internal/samplernames: fixes a colliding sampler name

[yuanyuanzhao3]

sampler name 9 was reserved for OTel ingestion but not documented.
The new sampler for remote user rule also uses 9. This fixes the collide.

What does this PR do?

Motivation

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
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[darccio]

As discussed with @yuanyuanzhao3, the current values are not yet in use. Approved.