[3.15] opentelemetry — enable on Python 3.15

[vlad-scherbich]

Tracked under parent: #17809

Tier: B
Section: API SDK — @DataDog/apm-sdk-capabilities-python

---

Original row from the parent tracker:

• opentelemetry — re-pin opentelemetry-exporter-otlp once it ships 3.15

---

To claim this row, self-assign on this issue (top-right "Assignees" → "assign yourself") or leave a Taking this comment.

To close this row, open a PR using the python_315_bump template (added in #17791; open via ?template=python_315_bump.md) and include Closes #<this-issue-number> in the description. That auto-closes this issue on merge, which auto-flips the corresponding checkbox on the parent tracker (#17809).