chore: Refactoring inconsistent naming and unnecessary model type (#592)

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# Description
<!-- Briefly describe the motivation for the change. Please include
illustrations where appropriate. -->
This PR mainly do refactoring to ml observability related code.
Following are the issues:
* Inconsistent field name between `InferenceSchema` and `PyfuncV3Model`
`ModelInput` and `ModelOutput`. In `InferenceSchema` unique identifier
for each prediction is defined in `row_id_column` where in `ModelInput`
and `ModelOutput` are stored in `prediction_ids`. To make the term
consistent we will change `prediction_ids` into `row_ids`
* Initially we add new model type when a model wants to onboard to ml
observability, but this is necessary user just need to implement
`PyfuncV3Model` instead of old `PyFuncModel` and use existing `pyfunc`
model type
* Update documentation on model schema and model observability

# Modifications
<!-- Summarize the key code changes. -->
* Remove all the code that using `pyfunc_v3` as model type
* `python/sdk/merlin/pyfunc.py` -> Add `row_ids` on `ModelInput` and
`ModelOutput`, not remove `prediction_ids` yet to support backward
compatibility
# Tests
<!-- Besides the existing / updated automated tests, what specific
scenarios should be tested? Consider the backward compatibility of the
changes, whether corner cases are covered, etc. Please describe the
tests and check the ones that have been completed. Eg:
- [x] Deploying new and existing standard models
- [ ] Deploying PyFunc models
-->

# Checklist
- [x] Added PR label
- [ ] Added unit test, integration, and/or e2e tests
- [ ] Tested locally
- [x] Updated documentation
- [ ] Update Swagger spec if the PR introduce API changes
- [ ] Regenerated Golang and Python client if the PR introduces API
changes

# Release Notes
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```release-note

```

api/api/validator.go

@@ -33,14 +33,12 @@ func (fv *funcValidate) validate() error {
 }
 
 var supportedUPIModelTypes = map[string]bool{
-	models.ModelTypePyFunc:   true,
-	models.ModelTypeCustom:   true,
-	models.ModelTypePyFuncV3: true,
+	models.ModelTypePyFunc: true,
+	models.ModelTypeCustom: true,
 }
 
 var supportedObservabilityModelTypes = []string{
 	models.ModelTypePyFunc,
-	models.ModelTypePyFuncV3,
 	models.ModelTypeXgboost,
 }