Standardizing timeout calculation in measurement consumer collect to nanoseconds

[mdcg]

Description

I made some changes to standardize the timeout calculation in the "collect" method of the "measurement consumer" to nanoseconds. The default_timeout_millis was in milliseconds and the remaining_time in nanoseconds, and shortly after, there was a comparison between these two values with "different bases" to update the timeout_millis value of the CallbackOptions.

I also updated some sections to use scientific notation instead of exponentiation.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Tested only using the existing tests. I did not create any new ones.

Does This PR Require a Contrib Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: mdcg / name: Mauro de Carvalho (71fc817, c35bafb, a4a836d, b69dbc6, 79cabe8, 0260d64, 119abc5)
• ✅ login: emdneto / name: Emídio Neto (d9b13f1)

[emdneto]

Care to fix lint and add CHANGELOG entry?

[mdcg]

@emdneto I removed the test I had created because I thought better of it and found it unnecessary. If we just test whether the CallbackOptions timeout_millis value is less than 10000, it is enough.