rewrite the common.sh helper script

In the past, the script seemed to be here to help to prepare environment in containers.
However, as the complexity of this template increases, I decided to rewrite the script to prepare uniform environment in any case.

shared/templates/grub2_bootloader_argument/tests/common.sh

@@ -1,14 +1,11 @@
 #!/bin/bash
 
-# We need to mock these files if they do not exist yet
-# Because:
-# - it is not possible to setup kernel / grub env properly in containerized env
-# - even if it would be possible, it takes long time
-
+# this file prepares unified test environment used by other scenarios
 # These should be tuned per product to match defaults
 
+{{% if product in ["ol8", "rhel8"] -%}}
 mkdir -p /boot/grub2
-if [ ! -f /boot/grub2/grubenv ]; then
+rm -f /boot/grub2/grubenv
 	# File size must be exactly 1KiB
 	{
 		echo '# GRUB Environment Block'
@@ -18,10 +15,11 @@ if [ ! -f /boot/grub2/grubenv ]; then
 		dd if=/dev/zero bs=1K count=1 | tr '\0' '#'
 	} > /boot/grub2/grubenv
 	truncate --size=1K /boot/grub2/grubenv
-fi
+{{% endif %}}
+
 
 mkdir -p /etc/default
-if [ ! -f /etc/default/grub ]; then
+rm -f /etc/default/grub
 	{
 		echo 'GRUB_CMDLINE_LINUX="rhgb ro ouiet"'
 		echo 'GRUB_CMDLINE_LINUX_DEFAULT="rhgb ro quiet mock"'
@@ -31,12 +29,11 @@ if [ ! -f /etc/default/grub ]; then
 		echo 'GRUB_ENABLE_BLSCFG=true'
 		echo 'GRUB_TIMEOUT=30'
 	} > /etc/default/grub
-fi
 
+{{% if product in ["fedora", "ol8", "ol9", "rhel8", "rhel9", "rhel10"] -%}}
 mkdir -p /boot/loader/entries
 shopt -s nullglob
-boot_loader_entries=(/boot/loader/entries/*.conf)
-if [ "${#boot_loader_entries[@]}" -eq 0 ]; then
+rm -f /boot/loader/entries/*.conf
 	{
 		echo 'title OS 1'
 		echo 'version 5.0'
@@ -46,4 +43,4 @@ if [ "${#boot_loader_entries[@]}" -eq 0 ]; then
 		echo 'grub_users $grub_users'
 		echo 'grub_arg --unrestricted'
 	} > /boot/loader/entries/mock.conf
-fi
+{{%- endif -%}}