gha: Skip non-relevant checks on pr or merge_group

[mramotowski]

Summary

How to test

Checklist

• I have added unit tests to cover my changes.​
• I have added integration tests to cover my changes.​
• I have ran e2e tests and there is no issues.
• I have added the description of my changes into CHANGELOG in my target branch (e.g., CHANGELOG in develop).​
• I have updated the documentation in my target branch accordingly (e.g., documentation in develop).
• I have linked related issues.

License

• I submit my code changes under the same Apache License that covers the project.
  Feel free to contact the maintainers if that's a concern.
• I have updated the license header for each file (see an example below).

# Copyright (C) 2025 Intel Corporation
# SPDX-License-Identifier: Apache-2.0

[Copilot]

Pull Request Overview

Optimizes GitHub Actions workflows by introducing conditional execution based on file changes and consolidating security scans. The PR restructures existing workflows to avoid running unnecessary checks when irrelevant files are modified, adds merge_group triggers, and separates security scanning into a dedicated workflow.

• Added file path checking to conditionally run workflow jobs based on changed files
• Introduced merge_group triggers and consolidated security scans into a separate workflow
• Added required_check jobs to aggregate workflow results for proper status reporting

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
.github/workflows/ui-lint-and-test.yaml	Added conditional execution based on file changes and required status check aggregation
.github/workflows/pr-security-scan.yaml	New dedicated workflow for security scans on pull requests
.github/workflows/lib-lint-and-test.yaml	Restructured with conditional execution and moved security scans to separate workflow
.github/workflows/build.yaml	Added file change detection and improved PR comment conditions
.github/workflows/backend-lint-and-test.yaml	Added conditional execution with path checking and required status aggregation

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[leoll2]

LGTM, ty

[Copilot]

Pull Request Overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

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