fix: report info-flag should not error when app undeployed

Several plugin `:report` subcommands erroneously failed with `not deployed` when an info-flag matched a property that was empty. Empty values are legitimate for configuration properties pre-deploy and the `--format json` path already returns them without error. Remove the `value_exists` check across nginx, checks, git, certs, scheduler-docker-local, and the builder-* plugins so the info-flag form behaves consistently with the JSON form.

plugins/builder-lambda/internal-functions

@@ -88,7 +88,6 @@ cmd-builder-lambda-report-single() {
       fi
     done
     [[ "$match" == "true" ]] || dokku_log_fail "Invalid flag passed, valid flags:${valid_flags}"
-    [[ "$value_exists" == "true" ]] || dokku_log_fail "not deployed"
   fi
 }