Introduce a flag that skips tag duplicate removal logic

[sungjujin]

This pull request primarily introduces a new feature to the Engine struct in engine.go which allows the skipping of duplicate tag removal in the metrics reporting process. This feature is tested in engine_test.go.

The most important changes are:

New feature:

• engine.go: Added a new boolean field SkipTagDuplicateRemoval to the Engine struct. This field controls whether the engine should skip the removal of duplicate tags from the tags list before sending.

Feature integration:

• engine.go: Modified the measure and ReportAt methods of the Engine struct to check the SkipTagDuplicateRemoval field before removing duplicate tags. [1] [2]

Testing:

• engine_test.go: Added a new test scenario in TestEngine to test the behavior when SkipTagDuplicateRemoval is set.
• engine_test.go: Implemented a new test function testEngineSkipTagDuplicateRemoval to test the new feature.

Contexts

https://twilio.slack.com/archives/CPLTV1V9A/p1720735336325819

[sungjujin]

@kevinburkesegment would you please review again? Thank you!

[sungjujin]

@kevinburkesegment I just wanted to follow up. Could you please review this PR when you have a moment? Thank you so much!