test: Drop --lets-encrypt-folder from test.py (#5455)

When we first deployed certificates from letsencrypt, we did not know
about the "live" folder, which contains helpful symlinks to the latest
certificate. Instead, we were copying the entire "archive" folder, which
contains even old certs, then searching that folder for the latest
version. We should be using the "live" folder instead, letting certbot
maintain the symlinks. This means there is no need for
--lets-encrypt-folder in test.py.

.github/workflows/selenium-lab-tests.yaml

@@ -251,7 +251,8 @@ jobs:
           python3 build/test.py \
               --no-build \
               --reporters spec --spec-hide-passed \
-              --lets-encrypt-folder /etc/shakalab.rocks \
+              --tls-key /etc/letsencrypt/live/karma.shakalab.rocks/privkey.pem \
+              --tls-cert /etc/letsencrypt/live/karma.shakalab.rocks/fullchain.pem \
               --hostname karma.shakalab.rocks \
               --port $KARMA_PORT \
               --grid-config build/shaka-lab.yaml \

build/test.py

@@ -358,11 +358,6 @@ def __init__(self, description):
     networking_commands.add_argument(
         '--tls-cert',
         help='Specify a TLS cert to serve tests over HTTPs.')
-    networking_commands.add_argument(
-        '--lets-encrypt-folder',
-        help="Specify a Let's Encrypt folder to search for the latest key and "
-             "cert, to serve tests over HTTPs.  This overrides --tls-key and "
-             "--tls-cert.")
 
 
     pre_launch_commands.add_argument(
@@ -441,26 +436,6 @@ def ParseArguments(self, args):
       else:
         self.karma_config['capture_timeout'] = LOCAL_CAPTURE_TIMEOUT
 
-    self._HandleLetsEncryptConfig()
-
-  def _HandleLetsEncryptConfig(self):
-    folder = self.parsed_args.lets_encrypt_folder
-    if not folder:
-      return
-
-    max_serial_number = 0
-    # Go through the contents of the folder to find the latest key & cert.
-    for file_name in os.listdir(folder):
-      matches = re.match(r'(?:privkey|fullchain)(\d+).pem', file_name)
-      if matches:
-        serial_number = int(matches.group(1))
-        max_serial_number = max(max_serial_number, serial_number)
-
-    self.karma_config['tls_key'] = os.path.join(
-        folder, 'privkey{}.pem'.format(max_serial_number))
-    self.karma_config['tls_cert'] = os.path.join(
-        folder, 'fullchain{}.pem'.format(max_serial_number))
-
   def ResolveBrowsers(self, default_browsers):
     """Decide what browsers we should use.