Reducing duplicated values on values files for SiaB

Reduced the amount of duplicated values between seba-ponsim values file.
To deploy, for example, the latest of seba-ponsim, now both seba-ponsim.yaml and seba-pomsim-latest.yaml values files need to be used with the specified order.
Makefile for SiaB is modified accordingly in the patch https://gerrit.opencord.org/#/c/16743/.
Also:
- removed stratumEnabled value from Mininet chart and added mnStratumSwitchCount
- moved bngAppUrl and bngAppVersion values on root of values file

Change-Id: I26b8e91f868646adc06f2c1feea72b333defd487
diff --git a/xos-profiles/seba-services/Chart.yaml b/xos-profiles/seba-services/Chart.yaml
index 5f30e70..aa31042 100644
--- a/xos-profiles/seba-services/Chart.yaml
+++ b/xos-profiles/seba-services/Chart.yaml
@@ -17,7 +17,7 @@
 name: seba-services
 description: A Helm chart for XOS's "SEBA" profile
 icon: https://guide.opencord.org/logos/cord.svg
-version: 1.4.2
+version: 1.4.3
 
 # xosproject/tosca-loader version
 appVersion: 1.3.1