arrow

GH-35943: [Dev] Ensure link issue works when PR body is empty (#36460)

### Rationale for this change

Fix a bug when PR body is empty and Dev workflow fails.

### What changes are included in this PR?

Ensure the link issue comment works in case of description being empty.

### Are these changes tested?

I have tested it on my fork here: https://github.com/raulcd/arrow/pull/81

### Are there any user-facing changes?

No
* Closes: #35943

Authored-by: Raúl Cumplido <raulcumplido@gmail.com>
Signed-off-by: Raúl Cumplido <raulcumplido@gmail.com>