WATCH no longer ignores keys which have expired for MULTI/EXEC. (#7920)

This wrong behavior was backed by a test, and also documentation, and dates back to 2010.
But it makes no sense to anyone involved so it was decided to change that.

Note that 3b031b1 (invalidate watch on expire on access) was released in 6.0 RC2
and 62a3ec8 released in in 6.0.0 GA (invalidate watch when key is evicted).
both of which do similar changes.

(cherry picked from commit 44bcbed2eed8577e7634e04817c4a75f9b722a62)

src/expire.c

@@ -64,7 +64,7 @@ int activeExpireCycleTryExpire(redisDb *db, dictEntry *de, long long now) {
             dbSyncDelete(db,keyobj);
         notifyKeyspaceEvent(NOTIFY_EXPIRED,
             "expired",keyobj,db->id);
-        trackingInvalidateKey(NULL,keyobj);
+        signalModifiedKey(NULL, db, keyobj);
         decrRefCount(keyobj);
         server.stat_expiredkeys++;
         return 1;

tests/unit/multi.tcl

@@ -221,7 +221,7 @@ start_server {tags {"multi"}} {
         r exec
     } {}
 
-    test {WATCH will not consider touched expired keys} {
+    test {WATCH will consider touched expired keys} {
         r del x
         r set x foo
         r expire x 1
@@ -230,7 +230,7 @@ start_server {tags {"multi"}} {
         r multi
         r ping
         r exec
-    } {PONG}
+    } {}
 
     test {DISCARD should clear the WATCH dirty flag on the client} {
         r watch x