test: improve test coverage

src/contact/contact.controller.spec.ts

src/contact/contact.controller.ts

src/contact/contact.service.spec.ts

src/parameters/parameters.controller.spec.ts

src/parameters/parameters.service.spec.ts

src/temp-user/temp-user.service.ts

src/users/controllers/users.controller.spec.ts

src/users/controllers/users.controller.ts

src/users/dto/create-user.dto.ts

src/users/services/users.service.spec.ts

src/users/services/users.service.ts

test/mock/data/users.mock.data.ts

test/mock/services/mailer.mock.service.ts