fix(remote-build): ignore dangling symlinks

[bepri]

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Fixes #1103.

[bepri]

Every test that needed this mock was already directly requesting it, but the autouse broke my new test

[Copilot]

Pull request overview

Fixes remote-build failing when the project directory contains dangling symlinks by adjusting how the remote-build worktree repository is created, and documenting the fix.

Changes:

• Update WorkTree.init_repo() to avoid crashing during repository copy when dangling symlinks are present.
• Adjust unit tests around worktree initialization and add coverage for dangling-symlink scenarios.
• Add a changelog entry for the remote-build symlink handling fix.

Reviewed changes

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

File	Description
craft_application/remote/worktree.py	Changes how the project tree is copied into the remote-build worktree repo.
tests/unit/remote/test_worktree.py	Updates fixtures and adds a dangling-symlink unit test for worktree init.
docs/reference/changelog.rst	Documents the remote-build dangling-symlink behavior change in the changelog.

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[bepri]

Duplicate of #1100