ref(uptime): Add `_ms` suffix to timestamps

[evanpurkhiser]

Will help make things more clear

[github-actions[bot]]

versions in use:

The following repositories use one of the schemas you are editing. It is recommended to roll out schema changes in small PRs, meaning that if those used versions lag behind the latest, it is probably best to update those services before rolling out your change.

• getsentry/uptime-checker: rust:sentry-kafka-schemas==0.1.99 (upgrade)
• getsentry/sentry: pip:sentry-kafka-schemas==0.1.93 (upgrade)

latest version: 0.1.100

changes considered breaking

**schemas/uptime-results.v1.schema.json** - Added a new property, but the consumer has been ignoring additional properties so far. This is probably still fine, but please double-check that the producer does not already send this property with a different type in practice than you defined in this schema. ``` {"path": "", "change": {"PropertyAdd": {"lhs_additional_properties": true, "added": "actual_check_time_ms"}}} ``` - Added a new property, but the consumer has been ignoring additional properties so far. This is probably still fine, but please double-check that the producer does not already send this property with a different type in practice than you defined in this schema. ``` {"path": "", "change": {"PropertyAdd": {"lhs_additional_properties": true, "added": "scheduled_check_time_ms"}}} ``` - ``` {"path": "", "change": {"RequiredAdd": {"property": "actual_check_time_ms"}}} ``` - ``` {"path": "", "change": {"RequiredAdd": {"property": "scheduled_check_time_ms"}}} ```

benign changes

**schemas/uptime-results.v1.schema.json** - Removed a property `actual_check_time` from ``, but it is still accepted via `additionalProperties=true` ``` {"path": "", "change": {"PropertyRemove": {"lhs_additional_properties": true, "removed": "actual_check_time"}}} ``` - Removed a property `scheduled_check_time` from ``, but it is still accepted via `additionalProperties=true` ``` {"path": "", "change": {"PropertyRemove": {"lhs_additional_properties": true, "removed": "scheduled_check_time"}}} ``` - ``` {"path": "", "change": {"RequiredRemove": {"property": "actual_check_time"}}} ``` - ``` {"path": "", "change": {"RequiredRemove": {"property": "scheduled_check_time"}}} ```

⚠️ This PR contains breaking changes. Normally you should avoid that and make your consumer backwards-compatible (meaning that updated consumers can still accept old messages). There are a few exceptions:

• If consumers already require these invariants in practice, and you're just adjusting the JSON schema to reality, ignore this warning.

• If you know what you are doing, this change could potentially be rolled out to producers first, but that's not a flow we support.