CMake: Remove warning about missing .ts file from qt_add_lrelease

Remove the warning "Translation file foo.ts does not exist", because
directly after the call we're creating an initial version of the file.

Change-Id: I62bd71c559343bec039607dd79ebd6e34c9d408a
Reviewed-by:  Alexey Edelev <[email protected]>
Reviewed-by: Alexandru Croitor <[email protected]>
(cherry picked from commit a713c0a)
Reviewed-by: Qt Cherry-pick Bot <[email protected]>

Author: jobor

src/linguist/Qt6LinguistToolsMacros.cmake

@@ -456,9 +456,6 @@ function(qt6_add_lrelease)
     set(qm_files "")
     foreach(ts_file ${ts_files})
         if(NOT EXISTS "${ts_file}")
-            message(WARNING "Translation file '${ts_file}' does not exist. "
-                "Consider building the target 'update_translations' to create an initial "
-                "version of that file.")
             _qt_internal_ensure_ts_file(TS_FILE "${ts_file}")
         endif()