fix(terraform): fix index out of range in load module #7314

[marceldevroed]

Adding test case and fix for index out of range issue

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Description

• ModuleLoaderRegistry now safely derives key/version when module_address lacks “:”.
• Eliminates IndexError from rsplit on module_address (no colon), which caused “Unable to load module in module_finder … list index out of range” warnings

Fixes #7314

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my feature, policy, or fix is effective and works
• New and existing tests pass locally with my changes