chore(env): adding node-label in node experiments and block-size in disk-fill (#450)

Signed-off-by: shubhamchaudhary <shubham@chaosnative.com>

Co-authored-by: Udit Gaurav <35391335+uditgaurav@users.noreply.github.com>

charts/generic/disk-fill/experiment.yaml

@@ -72,6 +72,11 @@ spec:
     - name: LIB
       value: 'litmus'
 
+    # provide the data block size
+    # supported unit is KB
+    - name: DATA_BLOCK_SIZE
+      value: '256'
+
     - name: TARGET_PODS
       value: ''