Refactor symlink handling in CacheEntryImpl to improve thread safety and clarity #1190

Job	Run time
Tests in Containers (ci-jupyter-container, ubuntu-latest, mcr.microsoft.com/devcontainers/univers...	4m 14s
Tests in Containers (ci-homebrew-container, ubuntu-latest, homebrew/brew, x86_64-unknown-linux-musl)	3m 24s
Tests (ubuntu-latest, x86_64-unknown-linux-musl, yes)	8m 46s
Tests (macos-latest, x86_64-apple-darwin, yes)	14m 14s
Tests (macos-14, aarch64-apple-darwin, yes)	14m 36s
Builds (windows-latest, x86_64-pc-windows-msvc)	4m 44s
Builds (macos-14, aarch64-apple-darwin, yes)	1m 52s
Builds (ubuntu-latest, x86_64-unknown-linux-musl, yes)	2m 1s
Tests (windows-latest, x86_64-pc-windows-msvc, yes)	7m 6s
Builds (windows-latest, aarch64-pc-windows-msvc)	4m 28s
Env Tests (ci-poetry-custom, windows-latest, x86_64-pc-windows-msvc)	5m 48s
Env Tests (ci-poetry-project, ubuntu-latest, x86_64-unknown-linux-musl)	2m 28s
Env Tests (ci-poetry-custom, ubuntu-latest, x86_64-unknown-linux-musl)	2m 25s
Env Tests (ci-poetry-project, windows-latest, x86_64-pc-windows-msvc)	6m 1s
Env Tests (ci-poetry-global, windows-latest, x86_64-pc-windows-msvc)	5m 34s
Env Tests (ci-poetry-global, ubuntu-latest, x86_64-unknown-linux-musl)	2m 22s
Builds (macos-latest, x86_64-apple-darwin, yes)	2m 38s
	1h 32m 41s

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