pgx sample test has some flaky failures

[olavloite]

pgx sample test has some flaky failures:

failed to connect to PGAdapter: failed to connect to `user=uid database=test-database`:
	127.0.0.1:32772 (localhost): failed to receive message: unexpected EOF
	[::1]:32772 (localhost): failed to receive message: unexpected EOF
--- FAIL: TestRunSample (0.[9](https://github.com/GoogleCloudPlatform/pgadapter/actions/runs/13215637721/job/36894578819?pr=2848#step:6:10)4s)
    pgx_sample_test.go:20: failed to run sample: failed to connect to `user=uid database=test-database`:
        	127.0.0.1:32772 (localhost): failed to receive message: unexpected EOF
        	[::1]:32772 (localhost): failed to receive message: unexpected EOF