[test] Fix bug in check_line_endings. NFC (#24503)

Looks like it was me that broke this back in 265908b.

Author: sbc100

test/line_endings.py

@@ -48,7 +48,7 @@ def check_line_endings(filename, expect_only=None, print_errors=True, print_info
     data = data.replace(b'\r\n', b'A')
     has_dos_line_endings = True
 
-  index = data.find(b'\r\n')
+  index = data.find(b'\n')
   if index != -1:
     unix_line_ending_example = data[index - 50:index + 50].replace(b'\r', b'\\r').replace(b'\n', b'\\n')
     unix_line_ending_count = data.count(b'\n')

test/test_other.py

@@ -9014,8 +9014,7 @@ def test_output_eol(self, params):
           expected_ending = '\n'
         else:
           expected_ending = '\r\n'
-
-        self.assertEqual(line_endings.check_line_endings(f, expect_only=expected_ending), 0, f'expected on ly {eol} line endingsn in {f}')
+        self.assertEqual(line_endings.check_line_endings(f, expect_only=expected_ending), 0, f'expected only {eol} line endings in {f}')
 
   def test_bad_memory_size(self):
     # if user changes INITIAL_MEMORY at runtime, the wasm module may not accept the memory import if