Improve log messages in forced photometry

Printing out the number of sources isn't as useful as printing
the data ID, especially when we already have other log messages
that print the same number.

python/lsst/pipe/tasks/forcedPhotCoadd.py

@@ -92,6 +92,8 @@ def attachFootprints(self, dataRef, sources, references, exposure, refWcs):
         """
         if self.config.footprintDatasetName is None:
             return ForcedPhotImageTask.attachFootprints(dataRef, sources, references, exposure, refWcs)
+        self.log.info("Loading deblended footprints for sources from %s, %s" %
+                      (self.config.footprintDatasetName, dataRef.dataId))
         fpCat = dataRef.get("%sCoadd_%s" % (self.config.coaddName, self.config.footprintDatasetName),
                             immediate=True)
         for refRecord, srcRecord in zip(references, sources):

python/lsst/pipe/tasks/forcedPhotImage.py

@@ -198,7 +198,7 @@ def run(self, dataRef):
         exposure = self.getExposure(dataRef)
         if exposure:
             references = list(self.fetchReferences(dataRef, exposure))
-            self.log.info("Performing forced measurement on %d sources" % len(references))
+            self.log.info("Performing forced measurement on %s" % dataRef.dataId)
             sources = self.generateSources(dataRef, references)
             self.attachFootprints(dataRef, sources, references=references, exposure=exposure, refWcs=refWcs)
             self.measurement.run(exposure, sources, references=references, refWcs=refWcs)