docs: fix outdated OpenTelemetry api example

[RYGRIT]

Problem

trace.SpanStatusCode.ERROR is not available in @opentelemetry/api 1.x.

deno check server.ts

TS2339 [ERROR]: Property 'SpanStatusCode' does not exist on type 'TraceAPI'.
          code: trace.SpanStatusCode.ERROR,
                      ~~~~~~~~~~~~~~

Changes

• Import SpanStatusCode directly from @opentelemetry/api
• Replace trace.SpanStatusCode.ERROR with SpanStatusCode.ERROR