change typeorm mongodb check

[ElfoLiNk]

PR Checklist

Please check if your PR fulfills the following requirements:

• [x] The commit message follows our guidelines: https://github.com/nestjs/terminus/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?

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

What is the current behavior?

typeorm MongoDB check create a new connection everytime and will cause more load on MongoDB

What is the new behavior?

Reuse connection and run ping command

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Other information

Tested manually in an environment health check passed from 40/50ms to 4/8ms:

[Nest] 8  - 05/04/2024, 9:49:48 AM     LOG [Network] 56b4c54a-c75a-4319-b9e9-12e3faa34542 - GET /health - 200 - 45ms
[Nest] 8  - 05/04/2024, 9:49:58 AM     LOG [Network] 4913ef85-c83b-4ce4-8b61-38cea5341868 - GET /health - 200 - 49ms

[Nest] 8  - 05/04/2024, 9:58:57 AM     LOG [Network] fb3aadb8-c4c0-4c15-b0cc-4302776747d4 - GET /health - 200 - 7ms
[Nest] 8  - 05/04/2024, 9:59:12 AM     LOG [Network] df4ad42a-d612-49a7-bfdf-27a9a6e0550f - GET /health - 200 - 5ms