treewide: drop shebang from non-executable target files

This drops the shebang from all target files for /lib and
/etc/uci-defaults folders, as these are sourced and the shebang
is useless.

While at it, fix the executable flag on a few of these files.

This does not touch ar71xx, as this target is just used for
backporting now and applying cosmetic changes would just complicate
things.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

target/linux/x86/base-files/lib/preinit/02_load_x86_ucode

@@ -1,4 +1,3 @@
-#!/bin/sh
 # Copyright (C) 2018 OpenWrt.org
 
 do_load_x86_ucode() {

target/linux/x86/base-files/lib/preinit/15_essential_fs_x86

@@ -1,4 +1,3 @@
-#!/bin/sh
 # Copyright (C) 2006-2010 OpenWrt.org
 # Copyright (C) 2010 Vertical Communications
 

target/linux/x86/base-files/lib/preinit/79_move_config

@@ -1,4 +1,3 @@
-#!/bin/sh
 # Copyright (C) 2012-2015 OpenWrt.org
 
 move_config() {

target/linux/x86/base-files/lib/preinit/81_upgrade_bootloader

@@ -1,5 +1,3 @@
-#!/bin/sh
-
 upgrade_bootloader() {
 	local diskdev