Removes sync minlines from syntax file

[pjio]

This setting breaks the syntax coloring in large PHP files for me. It's run via after/syntax/php/graphql.vim so due to similar files for other languages those might be affected as well (I have tested only PHP).

I'm not totally sure if ftplugin/graphql.vim might be a better place to set the value or if it shouldn't be overwritten at all.

At least I can say that setting the value inside the syntax file can cause a problem:

Steps to reproduce:

1. Open a large PHP file, e.g. https://raw.githubusercontent.com/WordPress/WordPress/master/wp-includes/ID3/getid3.lib.php
2. Jump to Line 1000 with :1000<cr>
3. The syntax coloring is broken

[jparise]

@pjio could you check if #72 fixes the problem you're seeing?

[jparise]

Closing in favor of #73