ORT- OVEP 1.19 PR-follow up (#21546)
### Description
Follow up PR for bug fixes on 1.19
### Motivation and Context
- Handles 1.19 docker file fixes.
- Sets the default file naming of epctx onnx model with _ctx.onnx as
suffix.
- Create epctx model directories if it doesn't exist.
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Co-authored-by: jatinwadhwa921 <110383850+jatinwadhwa921@users.noreply.github.com>
