chore: silence otelsdk warnings across build paths (#105)

## Summary

Silences the recurring `OpenTelemetry error: there is no package called 'otelsdk'` warnings during builds.

## Root cause

The `build-env-*` images configure an OTel exporter (traces/logs/metrics), but `otelsdk` (the R OTel SDK backend) isn't installed. pak's `otel` instrumentation therefore tries to load `otelsdk` on every run and logs the error, falling back to a no-op.

`OTEL_SDK_DISABLED=true` (already set in `build-one.Dockerfile`) does **not** help — the R `otel` package ignores it and gates purely on `OTEL_R_<SIGNAL>_EXPORTER` (then the standard `OTEL_<SIGNAL>_EXPORTER`). When that resolves to a real exporter (`otlp`/`http`/…) with no SDK present, you get the error.

## Fix

Set `OTEL_R_TRACES_EXPORTER`, `OTEL_R_LOGS_EXPORTER`, and `OTEL_R_METRICS_EXPORTER` to `none` so the R otel providers are clean no-ops:

- `docker/build-one.Dockerfile` — exported alongside the existing OTel var.
- `.crow/process-updates.yaml`, `weekly-rebuild-missing.yaml`, `build-all-versions.yaml`, `build-all-versions-install-deps.yaml` — added to each step's `environment` block.

Using the R-specific variables (not the standard `OTEL_*_EXPORTER`) keeps OTel intact for any non-R tooling in the images.

Reviewed-on: #105

docker/build-one.Dockerfile

@@ -30,6 +30,9 @@ RUN --mount=type=secret,id=b2_access,required=true \
     export GITHUB_PAT="$(cat /run/secrets/github_pat 2>/dev/null || true)" && \
     export GIT_TERMINAL_PROMPT=0 && \
     export OTEL_SDK_DISABLED=true && \
+    export OTEL_R_TRACES_EXPORTER=none && \
+    export OTEL_R_LOGS_EXPORTER=none && \
+    export OTEL_R_METRICS_EXPORTER=none && \
     XVFB=$(command -v xwfb-run 2>/dev/null || command -v xvfb-run || true); \
     XVFB_ARGS=""; \
     if command -v xwfb-run >/dev/null 2>&1; then dnf install -y -q weston 2>/dev/null; XVFB_ARGS="-c weston"; fi; \