fix(microservices): ensure all the amqp connections are closed properly

[yatin166]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

AMQP close connection method is asynchronous, in the current behaviour, connection were not properly closed for channel/server due to missing async/await.

Issue Number: N/A

What is the new behavior?

Added async/await when close() is called for channel/server in server-rmq so that all the connections are properly closed.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[coveralls]

Pull Request Test Coverage Report for Build 3571f57c-cf2a-42b6-8a56-aff228a29056

Details

• 3 of 13 (23.08%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 88.923%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/microservices/server/server-rmq.ts	3	13	23.08%

Totals
Change from base Build a9af550b-1747-4782-856a-aec11af85238:	0.0%
Covered Lines:	7177
Relevant Lines:	8071

---

💛 - Coveralls

[kamilmysliwiec]

[yatin166]

Fixed lint issue, can you check?

[kamilmysliwiec]

LGTM