move coverage to test_nightly

[mikaelarguedas]

as coverage doesnt depend on dependencies and test_latest takes forever

[codecov[bot]]

Codecov Report

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

Project coverage is 61.40%. Comparing base (07608ab) to head (ab20661).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## rolling #304 +/- ## ============================================ - Coverage 77.35% 61.40% -15.95% ============================================ Files 25 25 Lines 627 627 Branches 66 66 ============================================ - Hits 485 385 -100 - Misses 121 228 +107 + Partials 21 14 -7 ``` | [Flag](https://app.codecov.io/gh/ros2/sros2/pull/304/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros2) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/ros2/sros2/pull/304/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros2) | `61.40% <ø> (-15.95%)` | :arrow_down: | 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=ros2#carryforward-flags-in-the-pull-request-comment) to find out more.

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[mikaelarguedas]

for some reason I have the same odd behavior locally:

• if installed from packages or source: coverage sros2 coverage 78%
• if using the nightly archive and building

While test_generate policy passes it doesnt appear in coverage results.

Stalling this for now