Rename EVT cache hash to make context name unique

BuildEventTriggerCache sets up a context "EventTriggerCache" which
house a hash named "Event Trigger Cache", which in turn creates a
context with the table name.  This generated log output for memory
context dumps like below:

LOG:  level: 2; EventTriggerCache: 8192 total in 1 blocks; 7928 free (4 chunks); 264 used
LOG:  level: 3; Event Trigger Cache: 8192 total in 1 blocks; 2616 free (0 chunks); 5576 used

This renames the hash to ensure that the hash context has a unique
name for easier log reading and debugging.

Discussion: https://postgr.es/m/5EDC969E-CAE3-4CBD-965E-3B8A1294CFA4@yesql.se

src/backend/utils/cache/evtcache.c

@@ -121,7 +121,7 @@ BuildEventTriggerCache(void)
 	ctl.keysize = sizeof(EventTriggerEvent);
 	ctl.entrysize = sizeof(EventTriggerCacheEntry);
 	ctl.hcxt = EventTriggerCacheContext;
-	cache = hash_create("Event Trigger Cache", 32, &ctl,
+	cache = hash_create("EventTriggerCacheHash", 32, &ctl,
 						HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
 
 	/*