bin/editorconfig-el: Use --script

[monnier]

Emacs's master has been changed so as to avoid emitting the lexical-binding warning when using --script, so we can use that instead of the ugly hack. This also gives us --batch for free.

(main): Oh, and simplify it while we're at it.

[monnier]

For some reason, I'm not able to run the tests locally. They give me errors for:

The following tests FAILED:
          2 - meta_multiline (Failed)
          3 - star_single_ML (Failed)
          4 - star_zero_ML (Failed)
          5 - star_multiple_ML (Failed)
          7 - star_after_slash_ML (Failed)
          8 - star_matches_dot_file_after_slash_ML (Failed)
         10 - star_after_slash_ML_in_subdir (Failed)
         11 - star_matches_dot_file_after_slash_ML_in_subdir (Failed)
        133 - tab_width_default_ML (Failed)
        134 - tab_width_default_indent_size_tab_ML (Failed)
        135 - indent_size_default_ML (Failed)
        138 - indent_size_default_with_tab_width_ML (Failed)
        139 - lowercase_values1_ML (Failed)
        140 - lowercase_values2_ML (Failed)
        143 - repeat_sections_ML (Failed)
        144 - basic_cascade_ML (Failed)
        150 - blank_lines_between_properties_ML (Failed)
        154 - spaces_before_middle_property_ML (Failed)
        158 - comment_between_props_ML (Failed)
        163 - octothorpe_comment_between_props_ML (Failed)
        177 - parent_and_current_dir_ML (Failed)
        195 - unset_indent_size_ML (Failed)
Errors while running CTest

And LastTests.log shows things like:

"meta_multiline" start time: Nov 28 14:27 EST
Output:
----------------------------------------------------------
�[0m
answer=42�[0m
<end of output>
Test time =   0.17 sec
----------------------------------------------------------
Test Fail Reason:
Required regular expression not found. Regex=[^[
]*answer=42[ 	

]+$
]
"meta_multiline" end time: Nov 28 14:27 EST
"meta_multiline" time elapsed: 00:00:00
----------------------------------------------------------

Where the only oddity are those escape sequences around the output.

I"m pretty sure I ran them fine a few days ago and can't think of what I changed.
But I see now that it's really a problem on my side since the tests pass over on Github CI.