Bump @splunk/otel from 2.14.0 to 2.15.0 in /nodejs

Bumps [@splunk/otel](https://github.com/signalfx/splunk-otel-js) from 2.14.0 to 2.15.0.
- [Release notes](https://github.com/signalfx/splunk-otel-js/releases)
- [Changelog](https://github.com/signalfx/splunk-otel-js/blob/v2.15.0/CHANGELOG.md)
- [Commits](signalfx/splunk-otel-js@v2.14.0...v2.15.0)

---
updated-dependencies:
- dependency-name: "@splunk/otel"
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>