fix(kafka): fix kafka timestamps sent from application

[lsampras]

Type of Change

• Bugfix
• New feature
• Enhancement
• Refactoring
• Dependency updates
• Documentation
• CI/CD

Description

fixes #4706

Convert secs to millis when sending creation timestamp to kafka

Additional Changes

• This PR modifies the API contract
• This PR modifies the database schema
• This PR modifies application configuration/environment variables

Motivation and Context

• This will fix problems encountered down the pipeline with data retention

How did you test it?

• the timestamp listed in kafka-ui
• can't be tested without infra access and no visible changes on UI

Checklist

• I formatted the code cargo +nightly fmt --all
• I addressed lints thrown by cargo clippy
• I reviewed the submitted code
• I added unit tests for my changes where possible

[SanchithHegde]

Should we consider adding an extension trait if we'll use Unix timestamps in milliseconds frequently?

trait OffsetDateTimeExt {
    fn unix_timestamp_millis(self) -> i128;
}

impl OffsetDateTimeExt for time::OffsetDateTime {
    fn unix_timestamp_millis(self) -> i128 {
        self.unix_timestamp_nanos() / 1_000_000
    }
}

[lsampras]

Should we consider adding an extension trait if we'll use Unix timestamps in milliseconds frequently?

trait OffsetDateTimeExt {
    fn unix_timestamp_millis(self) -> i128;
}

impl OffsetDateTimeExt for time::OffsetDateTime {
    fn unix_timestamp_millis(self) -> i128 {
        self.unix_timestamp_nanos() / 1_000_000
    }
}

This conversion to timestamp millis is specific to kafka and would be abstracted away soon....
I'd rather the individual events provide me the PrimitiveDateTime/OffsetDateTime & kafka assumes it's representation