Bug 36400: (follow-up) remove option editorconfig from .prettierrc.js

Bug 36400: (follow-up) remove option editorconfig from .prettierrc.js

- The option doesn't seem do what it's intended for:
	- The debug logs still show options from the .editorconfig (which is actually what we want in this case).
- The option causes unwanted warnings when using the cli.
- In summary: we have to keep in mind that the rules are now hierarchical:
	1. .editorconfig
	2. .prettierrc.js

Signed-off-by: Brendan Lawlor <blawlor@clamsnet.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>