[SMP] Remove _nomulti experiments (#20033)

* [SMP] Remove `_nomulti` experiments

This commit removes the `_nomulti` variant experiments of
`uds_dogstatsd_to_api_nodist`. At this stage of the Agent we now believe that
nodist and nodist-nomulti experiments are indistinguishable in practice.

REF SMPTNG-11

Signed-off-by: Brian L. Troutwine <brian.troutwine@datadoghq.com>

* empty commit

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Signed-off-by: Brian L. Troutwine <brian.troutwine@datadoghq.com>

Author: blt