Say the query logger drops bound values (closes #535)

The comment on MaxAccessLogLineBytes said the GORM adapter logs each
statement with the client's parameter written into it. Its
ParamsFilter drops every bound value, so the statement is logged with
its placeholders. The comment now says so and keeps the parts that
still hold: the widest line spends two budgets and the adapter's test
checks it against this constant.

The assertBounded doc no longer claims each line was cut, and the
postReceiver doc no longer explains itself by a log size test that is
gone.

Model: opus-5-5

internal/gormlog/gormlog_test.go

@@ -146,7 +146,7 @@ func openDB(
 }
 
 // assertBounded holds every line the adapter wrote to the stated
-// ceiling and proves each was cut rather than merely short.
+// ceiling and proves no line carried a whole client value.
 func assertBounded(t *testing.T, out string) {
 	t.Helper()