tests: bluetooth: init: Remove duplicate prj_<x>.conf files

Remove duplicated prj.conf file.

prj_6, prj_7, prj_14 are identicall. Since prj_6.conf is unchanged,
keeping it.

prj_8, prj_9, prj_15 are identicall. Since prj_15.conf is
unchanged, keeping it.

Signed-off-by: Pavel Vasilyev <pavel.vasilyev@nordicsemi.no>
5 files changed