fix: support terraform tests in both test/ and tests/ directories

[mpsbp127]

Summary

• Expand CI terraform test discovery to support both test/** and tests/** directory conventions.
• Keep existing behavior for running terraform test, but prevent skipping tests when repositories use tests/ instead of test/.
  Why
• Different Terraform projects use either test/ or tests/ for test files.
• This change makes the workflow more robust and avoids false negatives where tests exist but are not executed due to directory naming.