[chore] add opentelemetry group to dependabot config

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 76.07%. Comparing base (1600b1a) to head (212f1d0). Report is 3 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #899 +/- ## ======================================= Coverage 76.07% 76.07% ======================================= Files 93 93 Lines 5856 5856 ======================================= Hits 4455 4455 Misses 1134 1134 Partials 267 267 ``` | [Flag](https://app.codecov.io/gh/grafana/tempo-operator/pull/899/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=grafana) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/grafana/tempo-operator/pull/899/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=grafana) | `76.07% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=grafana#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.