Revert "Don't use file-truepath in Eglot (bug#70036)"

Revert "Don't use file-truepath in Eglot (bug#70036)"

This reverts commit 08c80c45ddea17df87fc768a39dff353ccc13d3b.

It introduces bugs when a project contains symlinked files.  The server
will be informed of duplicate documents which are really the same and it
frequently has no means to deduplicate such information.

This leads to bugs such as excessive textDocument/references to a
function.

* lisp/progmodes/eglot.el (eglot-lsp-server): Revert change.
(eglot-uri-to-path): Revert change.
(eglot--on-shutdown): Revert change.
(eglot--managed-mode): Revert change.
(eglot-handle-notification textDocument/publishDiagnostics): Revert change.

(cherry picked from commit 306feb7d967ecea9c916dd6e25b2e84a3f1c714e)