Fix 1539: Helm v2.17.0 and set default value for stablerepourl

The --skip-repo option was not available. The version v2.17.0 is the
latest v2 version available.

Set https://charts.helm.sh/stable as the default stablerepourl value.

Change-Id: Ifdd85f0f891a705f56cdd50c6e4dbf95820d706f
Signed-off-by: David Garcia <david.garcia@canonical.com>
(cherry picked from commit 1d5c221862067b3b5b6e0555dcc4eb6c34e9a9f9)
diff --git a/installers/charm/lcm/config.yaml b/installers/charm/lcm/config.yaml
index f33d606..78efe2f 100644
--- a/installers/charm/lcm/config.yaml
+++ b/installers/charm/lcm/config.yaml
@@ -266,3 +266,7 @@
       during controller and model creation
       (bootstrap --config and add-model --config).
     type: string
+  vca_stablerepourl:
+    description: Stable repository URL for Helm charts
+    type: string
+    default: https://charts.helm.sh/stable