New classpath management system in launchers might break

[hamzaremmal]

Compiler version

main (f2829c3)

Issue example

#20631 changes the management of the classpath for the scaladoc.bat and scalac.bat commands. With this new structure, the length of the classpath is now much bigger than what is was previously and even reaching some of the limits set by windows : https://learn.microsoft.com/en-us/troubleshoot/windows-client/shell-experience/command-line-string-limitation

Discovered while debugging a workflow run in #20547

Expectation

We should reduce the length of the classpath variable to have enough margin to append other options and to avoid malfunctions

[bishabosha]

the technique is ultimately the same as before, just the number of entries grew in scaladocs classpath

[hamzaremmal]

Yes, this issue tackles the fact that now we have /maven2/.../file.jar instead of /lib/file.jar, therefore increasing the number of characters and reaching the limit set by Windows