fix(shell): show planned size in fs.mergeVolumes log to clarify size limit check (#8553)

The log message was comparing against the planned size of the destination
volume (including volumes already planned to merge into it) but only
displaying the raw volume size, making the output confusing when the
displayed sizes clearly didn't add up to exceed the limit.

weed/shell/command_fs_merge_volumes.go

@@ -244,10 +244,11 @@ func (c *commandFsMergeVolumes) createMergePlan(collection string, toVolumeId ne
 				fmt.Printf("volume %d is not compatible with volume %d\n", src, candidate)
 				continue
 			}
-			if c.getVolumeSizeBasedOnPlan(plan, candidate)+c.getVolumeSizeById(src) > c.volumeSizeLimit {
-				fmt.Printf("volume %d (%d MB) merge into volume %d (%d MB) exceeds volume size limit (%d MB)\n",
+			candidatePlannedSize := c.getVolumeSizeBasedOnPlan(plan, candidate)
+			if candidatePlannedSize+c.getVolumeSizeById(src) > c.volumeSizeLimit {
+				fmt.Printf("volume %d (%d MB) merge into volume %d (%d MB, %d MB with plan) exceeds volume size limit (%d MB)\n",
 					src, c.getVolumeSizeById(src)/1024/1024,
-					candidate, c.getVolumeSizeById(candidate)/1024/1024,
+					candidate, c.getVolumeSizeById(candidate)/1024/1024, candidatePlannedSize/1024/1024,
 					c.volumeSizeLimit/1024/1024)
 				continue
 			}