fix: otel schema url discrepancy

[VinozzZ]

Which problem is this PR solving?

When setting sender to otel, loadgen error out with below error

conflicting Schema URL: https://opentelemetry.io/schemas/1.24.0 and https://opentelemetry.io/schemas/1.25.0

Short description of the changes

• upgrade otel-config-go to the latest version that contains the latest schema url
• remove unused dependency clockwork

[VinozzZ]

dependent bot got it! https://github.com/honeycombio/loadgen/pull/59