Replace image form: arrange submit buttons in a one line

[0pdd]

The puzzle 1303-25f7ab3b from #1303 has to be resolved:

mystamps/src/main/webapp/WEB-INF/views/series/info.html

Line 163 in 4c2104a

<!--/* @todo #1303 Replace image form: arrange submit buttons in a one line */-->

The puzzle was created by Slava Semushin on 28-Apr-20.

[php-coder]

I've done that initially but because replace image button was before adding image button, it was activated during a form submission and it broke our tests. I didn't want to change them and use click instead of submit, so I decided to put buttons separately.

This won't be an issue after we migrate this form to React (#1328).