apacheGH-47948: [CI][Packaging][Deb] Add missing directory existent check (apache#47949)

### Rationale for this change

`Dir.empty?` fails with nonexistent directory.

### What changes are included in this PR?

Add `Dir.exist?` before `Dir.empty?`.

### Are these changes tested?

Yes.

### Are there any user-facing changes?

No.
* GitHub Issue: apache#47948

Authored-by: Sutou Kouhei <[email protected]>
Signed-off-by: Raúl Cumplido <[email protected]>

Author: kou

.github/workflows/package_linux.yml

@@ -29,6 +29,9 @@ on:
       - '.github/workflows/report_ci.yml'
       - 'cpp/**'
       - 'c_glib/**'
+      - 'dev/release/binary-task.rb'
+      - 'dev/release/verify-apt.rb'
+      - 'dev/release/verify-yum.rb'
       - 'dev/tasks/linux-packages/**'
       - 'format/Flight.proto'
     tags:
@@ -40,6 +43,9 @@ on:
       - '.github/workflows/report_ci.yml'
       - 'cpp/**'
       - 'c_glib/**'
+      - 'dev/release/binary-task.rb'
+      - 'dev/release/verify-apt.rb'
+      - 'dev/release/verify-yum.rb'
       - 'dev/tasks/linux-packages/**'
       - 'format/Flight.proto'
     types:

dev/release/binary-task.rb

@@ -1579,7 +1579,7 @@ def apt_update(base_dir, incoming_dir, merged_dir)
         base_dists_dir = "#{base_dir}/#{distribution}/dists/#{code_name}"
         merged_dists_dir = "#{merged_dir}/#{distribution}/dists/#{code_name}"
         rm_rf(merged_dists_dir)
-        if Dir.empty?(base_dists_dir)
+        if Dir.exist?(base_dists_dir) and Dir.empty?(base_dists_dir)
           mkdir_p(File.dirname(merged_dists_dir))
           cp_r(dists_dir, File.dirname(merged_dists_dir))
         else