RDS: modify_option_groups() now correctly parses OptionsToInclude

[bblommers]

See #8144

[codecov[bot]]

Codecov Report

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

Project coverage is 94.50%. Comparing base (b95bfe9) to head (5c3e427). Report is 16 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #8146 +/- ## ========================================== + Coverage 94.49% 94.50% +0.01% ========================================== Files 1150 1150 Lines 99025 99196 +171 ========================================== + Hits 93571 93745 +174 + Misses 5454 5451 -3 ``` | [Flag](https://app.codecov.io/gh/getmoto/moto/pull/8146/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=getmoto) | Coverage Δ | | |---|---|---| | [servertests](https://app.codecov.io/gh/getmoto/moto/pull/8146/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=getmoto) | `28.79% <16.66%> (-0.03%)` | :arrow_down: | | [unittests](https://app.codecov.io/gh/getmoto/moto/pull/8146/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=getmoto) | `94.47% <100.00%> (+0.01%)` | :arrow_up: | 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=getmoto#carryforward-flags-in-the-pull-request-comment) to find out more.

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[github-actions[bot]]

This is now part of moto >= 5.0.16.dev5