refactor(rdc): Remove `set_reset_group`
refactor(rdc): Remove `set_reset_group`

Combining `set_reset_group` and `set_reset_scenario` is not recommended.
`set_reset_scenario` is suggested method to define the reset scenario.
This commit removes `set_reset_group`.

Signed-off-by: Eunchan Kim <cb7bc7ceb22698f298c67faa994fd9ddf3cab298@opentitan.org>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan