Revert "install.sh: Force PATH to prefer /usr/local/bin and /usr/bin"
Revert "install.sh: Force PATH to prefer /usr/local/bin and /usr/bin"

Breaks macOS, which can have weird Python paths.

This reverts commit 1fc0ab2e60dbe5779873988c3f8ebd86f3bc0dd0.

jeff-allen-mongo/mut,jeff-allen-mongo/mut