profiles/follow up: consistent time format

[florianl]

This is a follow up for #239 (comment) around the request for a consistent time precision:

In ProfileContainer there are start_time_unix_nano and end_time_unix_nano. Should we have the same precision with timestamps in Sample and also use ns instead of ms?

oteps/text/profiles/0239-profiles-data-model.md

Lines 553 to 555 in dc619df

	// Timestamps associated with Sample represented in ms. These timestamps are expected
	// to fall within the Profile's time range. [optional]
	repeated uint64 timestamps = 13;

With Profile.time_nanos there is another timestamp in the message that uses nanosecond precision.

[arminru]

cc @open-telemetry/profiling-maintainers @open-telemetry/profiling-approvers

[mtwo]

Comment from the OTel maintainer meeting: could / should this be moved to a comment on the current Profiling PR in the OTLP repository?

[florianl]

This issue is linked in open-telemetry/opentelemetry-proto#534 (comment). As this particular issue is relevant to the specification, I did open the issue in this repository.

[petethepig]

Addressed in open-telemetry/opentelemetry-proto@f5b5897

[florianl]

Closing issue as resolved with open-telemetry/opentelemetry-proto@f5b5897.