Correct Unix socket path in conf.yaml.example

[lovasoa]

Update example configuration for Unix socket path.

What does this PR do?

Fixes the suggested postgres socket path

Motivation

The currently suggested path results in

    postgres (23.2.0)
    -----------------
      Instance ID: postgres:e3271050cd12e4fc [ERROR]
      Configuration Source: file:/etc/datadog-agent/conf.d/postgres.d/conf.yaml[0]
      Total Runs: 1
      Metric Samples: Last Run: 0, Total: 0
      Events: Last Run: 0, Total: 0
      Service Checks: Last Run: 0, Total: 0
      Average Execution Time : 17ms
      Last Execution Date : 2025-12-19 14:33:08.13 UTC (1766154788130)
      Last Successful Execution Date : Never
      metadata:
        config.source: /etc/datadog-agent/conf.d/postgres.d/conf.yaml[0]
        resolved_hostname: frankfurt
      Error: connection is bad: connection to server on socket "/var/run/postgresql/.s.PGSQL.5432/.s.PGSQL.5432" failed: Not a directory
        Is the server running locally and accepting connections on that socket?
      Traceback (most recent call last):
        File "/opt/datadog-agent/embedded/lib/python3.13/site-packages/datadog_checks/base/checks/base.py", line 1299, in run
          self.run_check_initializations()
          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
        File "/opt/datadog-agent/embedded/lib/python3.13/site-packages/datadog_checks/base/checks/base.py", line 1343, in run_check_initializations
          initialization()
          ~~~~~~~~~~~~~~^^
        File "/opt/datadog-agent/embedded/lib/python3.13/site-packages/datadog_checks/postgres/postgres.py", line 988, in _connect
          with self.db() as conn:
               ~~~~~~~^^
        File "/opt/datadog-agent/embedded/lib/python3.13/contextlib.py", line 141, in __enter__
          return next(self.gen)
        File "/opt/datadog-agent/embedded/lib/python3.13/site-packages/datadog_checks/postgres/postgres.py", line 294, in db
          self._db = self._new_connection(self._config.dbname)
                     ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
        File "/opt/datadog-agent/embedded/lib/python3.13/site-packages/datadog_checks/postgres/postgres.py", line 978, in _new_connection
          conn = TokenAwareConnection.connect(**kwargs)
        File "/opt/datadog-agent/embedded/lib/python3.13/site-packages/datadog_checks/postgres/connection_pool.py", line 111, in connect
          return super().connect(*args, **kwargs)
                 ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
        File "/opt/datadog-agent/embedded/lib/python3.13/site-packages/psycopg/connection.py", line 120, in connect
          raise last_ex.with_traceback(None)
      psycopg.OperationalError: connection is bad: connection to server on socket "/var/run/postgresql/.s.PGSQL.5432/.s.PGSQL.5432" failed: Not a directory
        Is the server running locally and accepting connections on that socket?

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[github-actions]

⚠️ Major version bump
The changelog type changed or removed was used in this Pull Request, so the next release will bump major version. Please make sure this is a breaking change, or use the fixed or added type instead.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.35%. Comparing base (eebd0e7) to head (eb8dca0).
⚠️ Report is 27 commits behind head on master.

Additional details and impacted files

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[sethsamuel]

@lovasoa Thanks for the contribution! Could you please update the changelog to a fixed?

[lovasoa]

@sethsamuel done :)

[lovasoa]

the failed tests do not seem related to the contents of the pr