Make the routewatch tests pass on a loaded host (closes #213)

Five prefix handler tests gave HandleMessage two seconds to apply a full
batch of 25,000 prefixes, which under the race detector on a loaded host
takes longer. A test now waits up to stepTimeout, 15 seconds, for each step
it expects.

The slowest tests filled production limits, such as the peering handler's
500,000 paths. The peering handler now takes its path limit, and the prefix
handler its limit on one write of the table's changes, as they take their
timer interval. Those tests give small limits, and the tests of the maximum
batch size lower it to one batch. This also fixes
#215.

The test helpers bound every wait, Stop included, so a test that hangs in
one fails with its own message.

Model: opus-5-5

internal/routewatch/prefixhandler_internal_test.go

@@ -237,9 +237,10 @@ func TestPrefixHandlerStopLogsNothingWhenItWroteEverything(t *testing.T) {
 	}
 }
 
-// longerThanAnyTest is a flush timer interval that no test lasts. A test whose
-// prefix, AS or peer handler must flush only when its batch is full and on Stop
-// gives it to newPrefixHandler, newASHandler or newPeerHandler.
+// longerThanAnyTest is a timer interval that no test lasts. A test gives it to
+// newPrefixHandler, newASHandler, newPeerHandler or newPeeringHandler when the
+// handler must write only when its batch is full, when the test says, or on
+// Stop.
 const longerThanAnyTest = time.Hour
 
 // prefixHandlerWithoutTimer returns a prefix handler that writes to store and
@@ -247,9 +248,11 @@ const longerThanAnyTest = time.Hour
 // NewPrefixHandler's flush goroutine, so the test flushes itself.
 func prefixHandlerWithoutTimer(store database.Store) *PrefixHandler {
 	return &PrefixHandler{
-		db:     store,
-		logger: logger.New(),
-		table:  routetable.New(routetable.Params{}),
+		db:                   store,
+		logger:               logger.New(),
+		table:                routetable.New(routetable.Params{}),
+		batchMaxSize:         prefixBatchMaxSize,
+		tableChangesPerWrite: maxTableChangesPerWrite,
 	}
 }