Fix a deprecation warning in EDM4hepFileReader.cpp

[jmcarcell]

isValid() (a check if a collection was found in a file, because if not an empty one is returned) has been changed to hasID() in AIDASoft/podio#860. Similar to what has been done in key4hep/EDM4hep#453. In one place we can remove it since size() == 1 implies isValid() or hasID(), otherwise the size would be 0.

BEGINRELEASENOTES

• Fix a deprecation warning in EDM4hepFileReader.cpp by changing collection.isValid() to collection.hasID().

ENDRELEASENOTES

[github-actions]

Test Results

   18 files     18 suites   6h 49m 1s ⏱️
  372 tests   372 ✅ 0 💤 0 ❌
3 278 runs  3 278 ✅ 0 💤 0 ❌

Results for commit 5dad64c.

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