Update /prediction python route to match odh documentation resource

[emilys314]

Closes https://issues.redhat.com/browse/RHOAIENG-11013

Description

Fixes the python notebook and flask code to match the readme.md and the odh resources documentation.

The odh documentation is a resource defined in the manifest, https://github.com/opendatahub-io/odh-dashboard/blob/main/manifests/common/apps/jupyter/deploy-python-model-quickstart.yaml so it's easier to just update this repository to follow what that is doing.

How Has This Been Tested?

1. git clone this repo / branch into a notebook
2. run through the notebook guide

Merge criteria:

• The commits are squashed in a cohesive manner and have meaningful messages.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work