Expand path of user provided file in runner

If user provides a file without absolute or relative path and
the file exists in any of the directories of the $LOAD_PATH
the `Kernel.load` method will load the latter one instead of the
intended one.

Expanding the path of the file forces Kernel to load the
correct file using its absolute path.

* Fixes rails#42007

Author: iridakos

railties/lib/rails/commands/runner/runner_command.rb

@@ -38,8 +38,9 @@ def perform(code_or_file = nil, *command_argv)
         if code_or_file == "-"
           eval($stdin.read, TOPLEVEL_BINDING, "stdin")
         elsif File.exist?(code_or_file)
-          $0 = code_or_file
-          Kernel.load code_or_file
+          expanded_file_path = File.expand_path code_or_file
+          $0 = expanded_file_path
+          Kernel.load expanded_file_path
         else
           begin
             eval(code_or_file, TOPLEVEL_BINDING, __FILE__, __LINE__)