providercache: include host in provider installation error

[radeksimko]

This is motivated by issues of the nature described in #31516 which we also noticed as part of our regular CI runs recently which runs terraform init for all ~250 official+verified providers.

https://github.com/hashicorp/terraform-ls/runs/7467545895?check_suite_focus=true#step:6:43

It aims to turn the following error:

Error while installing bluecatlabs/bluecat v1.0.0: local error: tls: bad record MAC

into

Error while installing bluecatlabs/bluecat v1.0.0: github.com: local error: tls: bad record MAC

The aim here is to communicate the fact that (often) such networking issues are between the user and GitHub, rather than the Terraform Registry - and if it is in fact the Registry then should allow us (and the user) to tell the errors apart.

This is similar to #30810

[github-actions]

Reminder for the merging maintainer: if this is a user-visible change, please update the changelog on the appropriate release branch.

[github-actions]

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