You're not structuring your commands correctly. Everywhere there's a space in a raw command line:
powershell.exe -File 'C:\Program Files\Inductive Automation\Ignition\data\git-auto-commit.ps1'
You need a new entry in the list you pass to system.util.execute or subprocess:
system.util.execute([
"powershell.exe",
"-File",
"'C:\Program Files\Inductive Automation\Ignition\data\git-auto-commit.ps1'"
])