Reword the Reporting front-end validation errors

Rewording reg/admin front-end errors complete in [#3124](https://github.com/bcgov/cas-registration/issues/3124) which then automatically completed some of these reporting forms

### Reporting module
Review Operation Information page
Replace Error message: Must not have fewer than 1 items
- [x] Operation representative
- [x] Reporting activities
- [x] Regulated products

Non Attributable Emissions page
Replace error message: must be equal to one of the allowed values with
"select a < field name >"
- [ ] Emission Category
- [ ] Additional Reporting Data page
Replace Error message: Must be number with

"Enter numbers only"
- [x] Electricity Generated field

Screenshots


Start in the Reporting module's Operation Information and Non Attributable Emissions pages, locating the validation messages listed in the issue. Update the remaining unchecked messages to the requested wording and verify that the completed cases still display correctly; the issue is done when the specified reporting form errors no longer show the generic text.

Written by the indexing model from the issue text.