base-files: handle packages alternatives when apk removes packages

base-files: handle packages alternatives when apk removes packages

On commit 3010ab8 ("base-files: add update_alternatives function") was
implemented the function to handle ALTERNATIVES when using APK (OPKG
handle it internally) but in commit bcc6415 ("base-files: add
compatibility for APK and OPKG") was only called when adding a package,
so call it also when removing packages.

While we are here, check for a more specific *.alternatives files instead
of *.list, and remove redundant "filelist" variable definition.

Fixes: bcc6415 ("base-files: add compatibility for APK and OPKG")
Fixes: https://github.com/openwrt/openwrt/issues/19090
Fixes: https://github.com/openwrt/openwrt/issues/16991
Reported-and-tested-by: Eric Fahlgren <ericfahlgren@gmail.com>
Signed-off-by: Mario Andrés Pérez <mapb_@outlook.com>
Link: https://github.com/openwrt/openwrt/pull/19093
Signed-off-by: Robert Marko <robimarko@gmail.com>