[BEAM-7877] Change the log level when deleting unknown temoprary file…

…s in FileBasedSink

Currently the log level is info. A new proposed log level is warning
since deleting unknown temporary files is a bad sign and sometimes leads
to data loss.

sdks/java/core/src/main/java/org/apache/beam/sdk/io/FileBasedSink.java

@@ -791,7 +791,10 @@ final void removeTemporaryFiles(
  FileSystems.match(Collections.singletonList(tempDir.toString() + "*")));
  for (Metadata matchResult : singleMatch.metadata()) {
  if (allMatches.add(matchResult.resourceId())) {
- LOG.info("Will also remove unknown temporary file {}", matchResult.resourceId());
+ LOG.warn(
+ "Will also remove unknown temporary file {}. This might indicate that other process/job is using "
+ + "the same temporary folder and result in data consistency issues.",
+ matchResult.resourceId());
  }
  }
  } catch (Exception e) {