JEventProcessorPODIO: Hide "Persisting collection ..." messages (#2148)

These are many and of low information density. We need to conserve AI
tokens.

### Briefly, what does this PR introduce?


### What kind of change does this PR introduce?
- [ ] Bug fix (issue #__)
- [ ] New feature (issue #__)
- [ ] Documentation update
- [ ] Other: __

### Please check if this PR fulfills the following:
- [ ] Tests for the changes have been added
- [ ] Documentation has been added / updated
- [ ] Changes have been communicated to collaborators

### Does this PR introduce breaking changes? What changes might users
need to make to their code?
No

### Does this PR change default behavior?
Yes

Author: veprbl

src/services/io/podio/JEventProcessorPODIO.cc

@@ -447,7 +447,7 @@ void JEventProcessorPODIO::FindCollectionsToWrite(const std::shared_ptr<const JE
     for (const std::string& col : all_collections) {
       if (m_output_exclude_collections.find(col) == m_output_exclude_collections.end()) {
         m_collections_to_write.push_back(col);
-        m_log->info("Persisting collection '{}'", col);
+        m_log->debug("Persisting collection '{}'", col);
       }
     }
   } else {