NUTCH-3192 Address Yetus detsecrets/blanks and SonarCloud security findings in config templates and DummySSL

[lewismc]

Fix for NUTCH-3192

• Replace shipped RabbitMQ URI defaults with amqp://localhost:5672/ (index-writers template, nutch-default rabbitmq.publisher.server.uri, indexer-rabbit README); document that a typical local broker uses the well-known guest/guest account and that operators must supply username:password@ when required
• Change DummySSL SSLContext protocol from "SSL" to "TLS" (keep intentional trust-all behavior for protocol-httpclient). Do we need to rename the Method and Class?
• Strip trailing whitespace in httpclient-auth.xml.template and replace example credentials with YOUR_USERNAME / YOUR_PASSWORD placeholders
• Mark S6736 as false positive in SonarCloud (masking regex in describe())

[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
24.2% Coverage on New Code
1.5% Duplication on New Code

See analysis details on SonarQube Cloud