Use hardcoded ArmoredPublicKey for TF binary installation

[andrewnester]

Changes

Use hardcoded ArmoredPublicKey for TF binary installation

Why

hashicorpPublicKey is HashiCorp's release-signing public key with self-signatures
refreshed on 2026-02-19 (expiration extended to ~2035).

The embedded key in hc-install v0.9.3 has a UserID self-signature that expired
on 2026-04-18, which breaks Terraform checksum verification. hc-install#355
added refreshed signatures, but go-crypto v1 only reads the first armored
block and keeps one SelfSignature per Identity, so the fix is a no-op when
relying on the embedded key. We pass this refreshed block to
releases.ExactVersion.ArmoredPublicKey directly.

Source: https://github.com/hashicorp/hc-install/blob/main/internal/pubkey/pubkey.go

Tests

Manually run rm -rf .databricks && databricks bundle deploy with and without the fix and confirm it helped

[adamfortuno-cubesmart]

We confirmed the fix resolved this issue. We installed and ran an instance of 0.266.0 to recreate the problem. Generating the error by running databricks bundle validate:

Error: error downloading Terraform: unable to verify checksums signature: openpgp: key expired

We upgraded the install to 0.266.1 and again executed the command, which completed successfully. We ran this on both Windows and Ubuntu.