ci: Use centralized add-license pre-commit hook

[yinggeh]

What does the PR do?

Switches the add-license pre-commit hook from the in-repo tools/add_copyright.py script to the centralized triton-inference-server/pre-commit-hooks repo, and removes the now-unused local script. This standardizes copyright-header validation/insertion across Triton repos.

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.

• ci

Related PRs:

Companion PRs applying the same centralized hook across the other Triton repositories:

• ci: Add centralized add-license pre-commit hook core#515
• ci: Add centralized add-license pre-commit hook client#906
• ci: Add centralized add-license pre-commit hook common#159
• ci: Add centralized add-license pre-commit hook backend#126
• ci: Add centralized add-license pre-commit hook identity_backend#35
• ci: Add centralized add-license pre-commit hook onnxruntime_backend#350
• ci: Add centralized add-license pre-commit hook python_backend#447
• ci: Add centralized add-license pre-commit hook pytorch_backend#199
• ci: Add centralized add-license pre-commit hook tensorrt_backend#123
• ci: Add centralized add-license pre-commit hook openvino_backend#118
• ci: Add centralized add-license pre-commit hook vllm_backend#132
• ci: Add centralized add-license pre-commit hook repeat_backend#18
• ci: Add centralized add-license pre-commit hook tutorials#156
• ci: Add centralized add-license pre-commit hook third_party#77

Where should the reviewer start?

.pre-commit-config.yaml (now references the shared hook) and the removal of tools/add_copyright.py.

Test plan:

• Run pre-commit run add-license --all-files locally and confirm it passes with consistent copyright headers.

• CI Pipeline ID:

Caveats:

The hook now resolves from triton-inference-server/pre-commit-hooks, which must be reachable when running pre-commit locally / in CI.

Background

Consolidates the copyright hook that previously lived in server/tools/add_copyright.py into a single shared pre-commit-hooks repo used by all Triton repos.

Related Issues: (use one of the action keywords Closes / Fixes / Resolves / Relates to)