Modify actor reminder registration to accommodate possible runtime change

## Describe the proposal
HOLD UNTIL CONFIRMED BY RUNTIME

## Describe the feature
[This issue](https://github.com/dapr/dapr/issues/9105) represents a regression in how actors are registered such that an existing reminder is no longer overwritten by default. I've advocated on the thread that the regression implication should be made the norm for this API much as it [was changed](https://github.com/dapr/dapr/issues/8402) on the Jobs API (likely related).

While this has not yet been committed to by the runtime maintainers, this issue should serve as a reminder that the SDK shape around reminder registration may need to be modified in a way that does not introduce a breaking change to accommodate (e.g., to provide an alternative method that throws if the reminder already exists).

## Release Note

RELEASE NOTE:
**ADD** Added method to throw if a reminder already exists on actor instead of strictly overwriting