Test Ajax.Request removal in most places

[timja]

jenkinsci/jenkins#7781

[timja]

All failures seem related to old test harness versions.

[timja]

Needs the following merged (and released):

• Bump plugin from 4.57 to 4.60 copyartifact-plugin#179
• Refresh plugin ant-plugin#117
• Update dependency org.jenkins-ci.plugins:plugin to v4.60 junit-plugin#518
• Bump parent pom matrix-auth-plugin#138
• Refresh plugin jdk-tool-plugin#59
• chore(deps): bump plugin from 4.59 to 4.60 saml-plugin#328
• Bump parent pom and bom ldap-plugin#229
• Refresh plugin matrix-project-plugin#150
• Upgrade plugin parent POM to 4.60 support-core-plugin#458
• Refresh plugin rebuild-plugin#135