fix: align OTel versions to v1.44.0 and use explicit e2e timeout fallback (#2791)

- Upgrade go.opentelemetry.io/otel/exporters/otlp/otlptrace,
  otlptracegrpc, and otel/sdk from v1.43.0 to v1.44.0 to match otel,
  otel/metric, and otel/trace already at v1.44.0
- Move E2E_TIMEOUT fallback from target-specific ?= into the e2e-run-%
  recipe via $(or $(E2E_TIMEOUT),20m) so the 20m default is explicit
  and the 25m override from test-experimental-e2e is unambiguous

Signed-off-by: Todd Short <tshort@redhat.com>
Co-authored-by: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>