[improve][misc] Upgrade Jetty to 12.1.13 - #26738

Motivation

Keep Jetty up to date. Jetty 12.1.13 contains fixes relevant to Pulsar's embedded Jetty usage:

• AbstractProxyServlet.filterServerResponseHeader returns existing value jetty/jetty.project#15548 — the proxy servlet now replaces/drops filtered proxy response headers instead of duplicating them (affects the proxy's AdminProxyHandler)
• Strengthened connection failure handling. jetty/jetty.project#15668 — strengthened HttpClient connection failure handling
• More precise *AuthenticationProtocolHandler.accept() handling in HttpClient for tunnel and same-protocol clear-text cases
• Introduce a limit to the number of HttpClient destinations jetty/jetty.project#15420 — support for HttpClient.maxDestinations
• CIDR pattern matching made case-insensitive

Modifications

• Upgrade Jetty from 12.1.12 to 12.1.13 in gradle/libs.versions.toml
• Update the Jetty jar versions in the server and shell distribution LICENSE.bin.txt files. No other transitive dependency versions changed (./gradlew checkBinaryLicense passes).

Verifying this change

• Make sure that the change passes the CI checks.

This change is already covered by existing tests, such as the Jetty-heavy proxy tests (*AdminProxyHandler*, FunctionWorkerRoutingTest, ProxyAdditionalServlet*, ProxyWithJwtAuthorizationTest), which pass locally.

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment