fix(data): remove strict typing for optimistic false

[yharaskrik]

Additional overload for .add() on NgRx Data Service causes issue when passing in boolean to isOptimistic. Remove overload as it should not be needed. Resolves #2928

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngrx/platform/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Cannot add a pass through function with a parameter of EntityActionOptions as boolean is not assignable to false

Closes #2928

What is the new behavior?

Looser typing allows passing EntityActionOptions through

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[ngrxbot]

Preview docs changes for b6a1760 at https://previews.ngrx.io/pr3020-b6a17609/