TT#16680 Add info output for successful yml check/validation

At the moment we provide no output for the end users, which
confuses them for the checks with and without the validation.
We should clearly report to users what has been checked.

Change-Id: Icc61744637345a1dc51fe8d8dd9bd3fd7f86824d

scripts/check

@@ -82,7 +82,9 @@ validate_config() {
     fi
   done
 
-  if [ "$rc" != "0" ] ; then
+  if [ "$rc" = "0" ] ; then
+    log_info "yml configs were validated successfully"
+  else
     if [ -n "${NO_VALIDATE:-}" ] ; then
       log_info "DANGEROUS ZONE: invalid configs detected, continue anyway due to option '--no-validate'"
     else
@@ -151,6 +153,7 @@ check_configs_conflicts
 
 check_shared_storage || exit $?
 
+log_info "configs were checked successfully"
 exit 0
 
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