Update packages/google-cloud-bigtable/google/cloud/bigtable/data/_metrics/handlers/opentelemetry.py

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: daniel-sanche

packages/google-cloud-bigtable/google/cloud/bigtable/data/_metrics/handlers/opentelemetry.py

@@ -130,10 +130,10 @@ def __init__(
         app_profile_id: str | None = None,
         client_uid: str | None = None,
         client_version: str | None = None,
-        instruments: _OpenTelemetryInstruments = _OpenTelemetryInstruments(),
+        instruments: _OpenTelemetryInstruments | None = None,
     ):
         super().__init__()
-        self.otel = instruments
+        self.otel = instruments or _OpenTelemetryInstruments()
         client_version = client_version or bigtable_version
         # fixed labels sent with each metric update
         self.shared_labels = {