fix(telemetry): make metrics best-effort so telemetry never crashes storage ops

[jayya2]

Description

Metric/trace exporter failures, unreachable telemetry processes, and OpenTelemetry
incompatibilities could raise from the telemetry path and crash daemon upload/download jobs.
This makes telemetry best-effort:

• Disable metrics/traces on any provider/exporter construction failure and cache the disabled
  state so (possibly expensive) construction isn't retried.
• Latch the synchronous record path so a failing record disables metrics for the storage client
  instead of crashing the storage operation.
• Skip metrics initialization entirely when MSC_TELEMETRY_DISABLED or OTEL_SDK_DISABLED is set.
• Fail fast with a clear error when the installed OTLP exporter is too old for the _otlp_mtls_vault
  mTLS client-certificate options, instead of an opaque TypeError.

Adds unit tests (disable-on-failure paths, record latch, env kill-switches) and documents disabling telemetry.

This is one half of a split (see the companion PR that declares explicit exposed methods on the
cross-process metric instrument proxies); the two are independent.

Checklist

• Development PR
  • .release_notes/.unreleased.md
    • Notable changes to the client from this PR have been added.

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