[GH-99] Add volume size for default scratch option

When user does not specify scratch = true specifically, we failed to add the volume option.
We should also check if work directory is network based and scratch is not specified.

plugins/nf-float/src/main/com/memverge/nextflow/FloatGridExecutor.groovy

@@ -446,18 +446,24 @@ fi
         return cmd
     }
 
+    private boolean shouldCheckImage(TaskRun task) {
+        final scratch = task.scratch
+        return useNetworkWorkdir() && scratch == null ||
+                scratch == true ||
+                isFusionEnabled()
+    }
+
     void addVolSize(List<String> cmd, TaskRun task) {
         long size = FloatConf.MIN_VOL_SIZE
 
         def disk = task.config.getDisk()
         if (disk) {
             size = Math.max(size, disk.toGiga())
         }
-        final fusionEnabled = isFusionEnabled()
-        if (fusionEnabled) {
+        if (isFusionEnabled()) {
             size = Math.max(size, FUSION_MIN_VOL_SIZE)
         }
-        if (task.scratch || fusionEnabled) {
+        if (shouldCheckImage(task)) {
             double inputSizeGB = (double) (getInputFileSize(task)) / 1024 / 1024 / 1024
             long minDiskSizeBasedOnInput = Math.round(inputSizeGB * DISK_INPUT_FACTOR)
             size = Math.max(size, minDiskSizeBasedOnInput)