tests/check_test_cases: Use ssl-opt.sh -l option instead of parsing

 * Use the newly added ssl-opt.sh -l option to list all the tests
   cases and their used parameters instead of having to parse the
   file to discover them. This avoids having to add further parsing
   complexity in the future as discussed in
   https://github.com/Mbed-TLS/mbedtls/pull/8080#issuecomment-1681064743

Signed-off-by: Tomás González <tomasagustin.gonzalezorlando@arm.com>
diff --git a/tests/scripts/check_test_cases.py b/tests/scripts/check_test_cases.py
index 1395d4d..be5b834 100755
--- a/tests/scripts/check_test_cases.py
+++ b/tests/scripts/check_test_cases.py
@@ -27,6 +27,8 @@
 import re
 import subprocess
 import sys
+import subprocess
+
 
 class Results:
     """Store file and line information about errors or warnings in test suites."""
@@ -100,17 +102,11 @@
     def walk_ssl_opt_sh(self, file_name):
         """Iterate over the test cases in ssl-opt.sh or a file with a similar format."""
         descriptions = self.new_per_file_state() # pylint: disable=assignment-from-none
-        with open(file_name, 'rb') as file_contents:
-            for line_number, line in enumerate(file_contents, 1):
-                # Assume that all run_test calls have the same simple form
-                # with the test description entirely on the same line as the
-                # function name.
-                m = re.match(br'\s*run_test\s+"((?:[^\\"]|\\.)*)"', line)
-                if not m:
-                    continue
-                description = m.group(1)
-                self.process_test_case(descriptions,
-                                       file_name, line_number, description)
+        listed = subprocess.run(['tests/ssl-opt.sh', '-l'],
+                                 capture_output=True)
+        listed = set(map(lambda x: x.rstrip(), listed.stdout.splitlines()))
+        for description in listed:
+            self.process_test_case(descriptions, file_name, None, description)
 
     def walk_compat_sh(self, file_name):
         """Iterate over the test cases compat.sh with a similar format."""