Reduced the logging level for the stack traces produced when resolvin…

…g external artifacts. (#6310)

In case of an IOException, only the message and the type of error is logged as a warning. The stack trace is logged only at the lowest level, so as to limit the amount of logs when there are many problematic artifacts.

base/src/com/google/idea/blaze/base/sync/workspace/ArtifactLocationDecoderImpl.java

@@ -98,8 +98,9 @@ public File decode(ArtifactLocation artifactLocation) {
           return realFile;
         }
       } catch (IOException ioException) {
-        LOG.warn("Failed to resolve real path for " + artifactLocation.getExecutionRootRelativePath(),
-            ioException);
+        LOG.warn("Failed to resolve real path for " + artifactLocation.getExecutionRootRelativePath() +
+                "\n" + ioException.getClass().getSimpleName() + ": " + ioException.getMessage());
+        LOG.trace(ioException);
       }
     }
     return null;