use allowlist for bool coercion in declarative config resource

Assisted-by: Claude Sonnet 4.6

Author: MikeGoldsmith

opentelemetry-sdk/src/opentelemetry/sdk/_configuration/_resource.py

@@ -34,7 +34,7 @@
 
 def _coerce_bool(value: object) -> bool:
     if isinstance(value, str):
-        return value.lower() not in ("false", "0", "")
+        return value.lower() in ("true", "1")
     return bool(value)