Terraform Binary Ignored With Tofu On Path

terraform_binary properly respected when both tofu and terraform are on PATH

A regression in command execution caching resulted in over-caching the STDOUT result of tofu --version when both tofu and terraform were available on PATH and terraform_binary was set. Early on in the execution flow, Terragrunt checks if OpenTofu is installed what its version is to determine if it supports setting of the automatic provider cache directory. This resulted in the value of terraform_binary being ignored for later version checks to assess compliance with terraform_version_constraint.

The version-detection cache used per run is now scoped to the binary that produced each entry, so the version recorded against an early default-binary resolution no longer leaks into the later resolution that honors terraform_binary.