fix(microservices): report correct buffer length in exception

[kim-sung-jee]

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?

MaxPacketLengthExceededException always reports length of 0

Issue Number: #15472

What is the new behavior?

MaxPacketLengthExceededException correctly reports the actual buffer length.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[coveralls]

Pull Request Test Coverage Report for Build 0bf7da57-9a2d-480b-be74-74e127c0ebfe

Details

• 0 of 2 (0.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.01%) to 88.902%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/microservices/helpers/json-socket.ts	0	2	0.0%

Totals
Change from base Build 52362f9b-3b1b-4350-80e5-95eab6af1468:	-0.01%
Covered Lines:	7282
Relevant Lines:	8191

---

💛 - Coveralls

[kamilmysliwiec]

LGTM