test: Add more test cases to validate model name

[mudit-eng]

What does the PR do?

This PR adds more test cases to validate model name while loading.

1. Test cover cases " .." and ".. ". Remove leading and trailing whitespace from model name before checking for path traversal characters.
2. Names with dots like "model..", "...", "..model" are valid according to the POSIX standard. Test checks those

Checklist

• PR title reflects the change and is of format <commit_type>: <Title>
• Changes are described in the pull request.
• Related issues are referenced.
• Populated github labels field
• Added test plan and verified test passes.
• Verified that the PR passes existing CI.
• Verified copyright is correct on all changed files.
• Added succinct git squash message before merging ref.
• All template sections are filled out.
• Optional: Additional screenshots for behavior/output changes with before/after.

Commit Type:

Check the conventional commit type
box here and add the label to the github PR.

• build
• ci
• docs
• feat
• fix
• perf
• refactor
• revert
• style
• test

Related PRs:

Changes in core: triton-inference-server/core#481

Where should the reviewer start?

Look at changes in core: triton-inference-server/core#481

Test plan:

Added test cases and verified they pass by running locally

• CI Pipeline ID:
  46042638
  (MLFlow passed, have to retry Input Validation as it failed due to different reason)

[pskiran1]

LGTM