update jetty version to match kafka-rest, pin additional jetty libraries

[janjwerner-confluent]

Problem

Parent pom defines outdated version of jetty that could lead to bringing outdated, vulnerable dependencies by connectors using kafka-connect-storage pom

Solution

Bump version of the dependency, specify dependencies in the dependencyManagement to instruct artifacts built using this pom to use the updated versions.

Does this solution apply anywhere else?

• [ ] yes
• [ ] no

If yes, where?

Test Strategy

Testing done:

• [ ] Unit tests
• [ ] Integration tests
• [ ] System tests
• [ ] Manual tests

Release Plan

[janjwerner-confluent]

stale, unreviewed since March