test: move common.PORT tests to sequential

Reasons:

- `test-async-wrap-getasyncid` binds a handle, so move to
  sequential because port cannot be already in use.
- `test-dgram-implicit-bind-failure` requires a hardcoded
  port number to properly send socket packet.
- `test-http-agent-uninitialized-with-handle` requires a
  hardcoded port number to properly send http request.
- `test-http-agent-uninitialized` requires a hardcoded port
  number to properly send http request.
- `test-net-localport` requires a hardcoded port number
  for assertions.

In addition this replaces two common.PORTs with a dynamic port.

PR-URL: https://github.com/nodejs/node/pull/15151


Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>