fix(global): respect custom VP_HOME #756

Job	Run time
Test install.sh (Linux ARM64 glibc via QEMU)	2m 40s
Test install.sh (Linux ARM64 musl via QEMU)	1m 31s
Test install.sh (Linux x64 musl)	21s
Test install.ps1 (Windows x64, PowerShell 5.1)	52s
Test install.sh (macOS ARM64)	15s
Test install.ps1 (minimum-release-age)	17s
Test install.ps1 (Windows ARM64)	49s
Test install.sh (Linux x64 glibc)	16s
Test vp-setup.exe (pwsh)	6m 29s
Test install.ps1 (Windows x64)	55s
Test install.sh (macOS x64)	1m 17s
Test install.ps1 (Windows x64, PowerShell 7.6)	1m 3s
Test install.sh (readonly shell config)	9s
	16m 54s

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