sleep,home: always initialize UnitFreezer if used

Previously, unit_freezer_new_freeze() would only return
UnitFreezer object if FreezeUnit() succeeds. This is not
ideal though, as a failed bus call doesn't mean the action
actually failed. E.g. a timeout might occur because pid1
is waiting for cgroup event from kernel, while the bus call
timeout was exceeded (#33269). In such a case, ThawUnit()
will never be called, resulting in frozen units remain that
way after resuming from sleep.

Therefore, let's get rid of unit_freezer_new_freeze(),
and make sure as long as unit freezer is involved, we'll
call ThawUnit() when we're done. This should make things
a lot more robust.

src/shared/bus-unit-util.c

@@ -3025,22 +3025,3 @@ int unit_freezer_freeze(UnitFreezer *f) {
 int unit_freezer_thaw(UnitFreezer *f) {
         return unit_freezer_action(f, false);
 }
-
-int unit_freezer_new_freeze(const char *name, UnitFreezer **ret) {
-        _cleanup_(unit_freezer_freep) UnitFreezer *f = NULL;
-        int r;
-
-        assert(name);
-        assert(ret);
-
-        r = unit_freezer_new(name, &f);
-        if (r < 0)
-                return r;
-
-        r = unit_freezer_freeze(f);
-        if (r < 0)
-                return r;
-
-        *ret = TAKE_PTR(f);
-        return 0;
-}

src/shared/bus-unit-util.h

@@ -45,5 +45,3 @@ int unit_freezer_new(const char *name, UnitFreezer **ret);
 
 int unit_freezer_freeze(UnitFreezer *f);
 int unit_freezer_thaw(UnitFreezer *f);
-
-int unit_freezer_new_freeze(const char *name, UnitFreezer **ret);