fix: Participant Sid starts with UT in Interaction Channel Participant

[dcanonmolina]

Fixes

According to our docs, the participant sid in the Flex's Interaction Channel Participant must start with UT as UTXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX https://www.twilio.com/docs/flex/developer/conversations/interactions-api/interaction-channel-participants?code-sample=code-wrap-up-agent-reservation&code-language=twilio-cli&code-sdk-version=5.x

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