Platform 24.6 PiT issues

[manolo]

Blockers

• PiT 24.6: Project does not work in JDK-21 mpr-demo#21
• React Router Future Flag warning flow#20527
• blocking beta release Flow auto layout not applied hilla#2928
• project not working with latest flow change mpr-demo#23
• Login view not shown for /# hilla#2954
• spring-petclinic is not compatible with vaadin 24.6.0.beta3 hilla#2955
• PiT 24.6: project does not work with previous version 24.5 mpr-demo#25
• https://vaadin.slack.com/archives/C01EJJNMAC9/p1733842048389869
• [PiT] switching between different views results in wrong url flow#20671

Non Blockers

• Navigating between Views cause application Error  hilla#3002
• https://github.com/vaadin/copilot-internal/issues/4010