ae.net.db: Fix DNS failure tests hanging on Windows

Use trailing dot ("nonexistent.invalid.") to mark the hostname as a
fully-qualified domain name. Without the dot, the Windows DNS resolver
appends suffixes from the search list (e.g. .internal.cloudapp.net on
Azure VMs), causing multiple DNS queries that each can take up to 10
seconds to time out.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: claude

net/db/mysql/package.d

@@ -2319,7 +2319,7 @@ debug(ae_unittest) unittest
 
     bool gotError = false;
     async({
-        auto mysql = new MySqlConnection("nonexistent.invalid", 3306, "user", "db", "pass");
+        auto mysql = new MySqlConnection("nonexistent.invalid.", 3306, "user", "db", "pass");
         try
             await(mysql.ready);
         catch (Exception e)

net/db/psql/package.d

@@ -1544,7 +1544,7 @@ debug(ae_unittest) unittest
 
 	bool gotError = false;
 	async({
-		auto pg = new PgSqlConnection("nonexistent.invalid", 5432, "user", "db", "pass");
+		auto pg = new PgSqlConnection("nonexistent.invalid.", 5432, "user", "db", "pass");
 		try
 			await(pg.ready);
 		catch (Exception e)