Fixed gettext usage:

- fixed gettext usage with .format() only for original text with %s
  - fixed typos
  - fixed translation yes/no buttons in the dialog.
  - improved translating sentences without "connecting" words (eg. see web/pgadmin/dashboard/static/js/dashboard.js,
     word 'cancel' needs to be translated in the Czech language as 'zrušit' but in another sentence as 'zrušení')
  - added gettext for text translations.

web/pgadmin/browser/server_groups/servers/pgagent/__init__.py

@@ -284,8 +284,7 @@ SELECT EXISTS(
                     status=410,
                     success=0,
                     errormsg=_(
-                        "Could not find the required parameter (%s)." % arg
-                    )
+                        "Could not find the required parameter (%s).") % arg
                 )
 
         status, res = self.conn.execute_void('BEGIN')

web/pgadmin/browser/server_groups/servers/pgagent/steps/static/js/pga_jobstep.js

@@ -305,7 +305,7 @@ define('pgadmin.node.pga_jobstep', [
             !_.isUndefined(val) && !_.isNull(val) &&
               String(val).replace(/^\s+|\s+$/g, '') == ''
           ) {
-            msg = gettext('Please select valid on error option .');
+            msg = gettext('Please select valid on error option.');
             this.errorModel.set('jstonerror', msg);
           } else {
             this.errorModel.unset('jstonerror');