shared: rename condition-util.[ch] to condition.[ch]

Now that we only have one file with condition implementations around, we
can drop the -util suffix and simplify things a bit.

src/network/networkd-netdev.h

@@ -25,7 +25,6 @@
 #include "hashmap.h"
 #include "list.h"
 #include "set.h"
-#include "condition-util.h"
 #include "in-addr-util.h"
 
 typedef struct NetDevVTable NetDevVTable;

src/network/networkd.h

@@ -37,7 +37,7 @@
 #include "hashmap.h"
 #include "list.h"
 #include "set.h"
-#include "condition-util.h"
+#include "condition.h"
 #include "in-addr-util.h"
 
 #define CACHE_INFO_INFINITY_LIFE_TIME 0xFFFFFFFFU