Fix flaky unit test for awsentity translator logics

[zhihonl]

Description of the issue

We currently have flaky unit test for awsentity translator. This is because Golang unit test does not guarantee sequential ordering based on the order the test is written in the code, so in this case if ECS test is ran first, it will set ECS singleton's region to something valid, then when OnlyProfile unit test runs, it is still considered in ECS mode so translator will still return nil for the translation

Description of changes

• Reset ECS singleton region variable.

License

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

Tests

Unit test

Requirements

Before commit the code, please do the following steps.

1. Run make fmt and make fmt-sh
2. Run make lint