helm-diff.sh: Reuse tool for all swh apps

Using another branch with a cherry-pick on that commit ^ (for testing purposes). It's working (diff shows changes as expected):

$ make helm-diff
./helm-diff.sh swh
[swh] Comparing changes between branches production and parametric-termination-grace-period...
Switched to branch 'production'
Your branch is up to date with 'origin/production'.
[swh] Generate config in production branch for swh/values/default.yaml...
[swh] Generate config in production branch for swh/values/production-cassandra.yaml...
[swh] Generate config in production branch for swh/values/production.yaml...
[swh] Generate config in production branch for swh/values/staging-cassandra.yaml...
[swh] Generate config in production branch for swh/values/staging.yaml...
Switched to branch 'parametric-termination-grace-period'
[swh] Generate config in parametric-termination-grace-period branch for swh/values/default.yaml...
[swh] Generate config in parametric-termination-grace-period branch for swh/values/production-cassandra.yaml...
[swh] Generate config in parametric-termination-grace-period branch for swh/values/production.yaml...
[swh] Generate config in parametric-termination-grace-period branch for swh/values/staging-cassandra.yaml...
[swh] Generate config in parametric-termination-grace-period branch for swh/values/staging.yaml...


------------- diff for swh/values/default.yaml -------------

No differences


------------- diff for swh/values/production-cassandra.yaml -------------

No differences


------------- diff for swh/values/production.yaml -------------

--- /tmp/swh-chart.swh.iVcrfVpe/production.yaml.before  2023-07-12 15:48:17.736140985 +0200
+++ /tmp/swh-chart.swh.iVcrfVpe/production.yaml.after   2023-07-12 15:48:18.168141683 +0200
@@ -1472,20 +1472,21 @@
       affinity:

         nodeAffinity:
           requiredDuringSchedulingIgnoredDuringExecution:
             nodeSelectorTerms:
             - matchExpressions:
               - key: swh/lister
                 operator: In
                 values:
                 - "true"
+      terminationGracePeriodSeconds: 3600
+ ```