Add more Scala 3 LSP tests for symbol search

[tgodzik]

Describe the bug

We removed testing of nightly compiler in out cross tests, since that proved to be a big burden. We need to make sure that we at least have a few tests making sure that symbol search is used correctly by the Scala 3 presentation compiler.

We might want to do that for Scala LTS Next or just nightly?

This is already partly tested in CompletionCrossLspSuite

Expected behavior

More tests!

Operating system

Linux

Editor/Extension

VS Code

Version of Metals

v1.3.0

Extra context or search terms

tests

[rochala]

Afaik we will have nightly for both LTS line and next. We should test for both if test suite is fast enough. If this is the case it should be run on every PR, which will ensure that Symbol Search is still working on both sides.