opentelemetry-exporter-otlp-proto-http: fix certificate_file=False being ignored

The constructor used  which caused
an explicitly passed False value to be discarded due to Python's falsy
evaluation. Use  check instead so that False (disable SSL
verification) is respected.

Author: SFernandoS

exporter/opentelemetry-exporter-otlp-proto-http/src/opentelemetry/exporter/otlp/proto/http/trace_exporter/__init__.py

@@ -90,7 +90,7 @@ def __init__(
                 environ.get(OTEL_EXPORTER_OTLP_ENDPOINT, DEFAULT_ENDPOINT)
             ),
         )
-        self._certificate_file = certificate_file or environ.get(
+        self._certificate_file = certificate_file if certificate_file is not None else environ.get(
             OTEL_EXPORTER_OTLP_TRACES_CERTIFICATE,
             environ.get(OTEL_EXPORTER_OTLP_CERTIFICATE, True),
         )