updated install file to set gin toolbar on update hook

[tjackson2113]

Solves part of 1139, set gin toolbar.

When running update, sets gin toolbar to be the sane default we provided previously.
4.x only, 5.x WIP.

[trubach]

I'm seeing an issue with the update. After running drush updb, the toolbar is not displaying correctly (see image below)

I think the issue is in the $config->set('classic_toolbar', TRUE); in the helper function. I believe it should be $config->set('classic_toolbar', 'vertical'); instead.

[trubach]

@tjackson2113 - please see the comments next to the code below.