drop support for using GlusterFS directly

As the GlusterFS project is unmaintained since a while and other
projects like QEMU also drop support for using it natively.

One can still use the gluster tools to mount an instance manually and
then use it as directory storage; the better (long term) option will
be to replace the storage server with something maintained though, as
PVE 8 will be supported until the middle of 2026 users have some time
before they need to decide what way they will go.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

src/PVE/API2/Storage/Scan.pm

@@ -43,7 +43,6 @@ __PACKAGE__->register_method({
 
         my $res = [
             { method => 'cifs' },
-            { method => 'glusterfs' },
             { method => 'iscsi' },
             { method => 'lvm' },
             { method => 'nfs' },
@@ -245,58 +244,6 @@ __PACKAGE__->register_method({
     },
 });
 
-# Note: GlusterFS currently does not have an equivalent of showmount.
-# As workaround, we simply use nfs showmount.
-# see http://www.gluster.org/category/volumes/
-__PACKAGE__->register_method({
-    name => 'glusterfsscan',
-    path => 'glusterfs',
-    method => 'GET',
-    description => "Scan remote GlusterFS server.",
-    protected => 1,
-    proxyto => "node",
-    permissions => {
-        check => ['perm', '/storage', ['Datastore.Allocate']],
-    },
-    parameters => {
-        additionalProperties => 0,
-        properties => {
-            node => get_standard_option('pve-node'),
-            server => {
-                description => "The server address (name or IP).",
-                type => 'string',
-                format => 'pve-storage-server',
-            },
-        },
-    },
-    returns => {
-        type => 'array',
-        items => {
-            type => "object",
-            properties => {
-                volname => {
-                    description => "The volume name.",
-                    type => 'string',
-                },
-            },
-        },
-    },
-    code => sub {
-        my ($param) = @_;
-
-        my $server = $param->{server};
-        my $res = PVE::Storage::scan_nfs($server);
-
-        my $data = [];
-        foreach my $path (sort keys %$res) {
-            if ($path =~ m!^/([^\s/]+)$!) {
-                push @$data, { volname => $1 };
-            }
-        }
-        return $data;
-    },
-});
-
 __PACKAGE__->register_method({
     name => 'iscsiscan',
     path => 'iscsi',