Fix argparse error for BooleanArgument with % in documentation

Python 3.14+ argparse treats % characters in help strings as format
specifiers. When service model documentation contains % (e.g., IAM's
UpdateAccountPasswordPolicy RequireSymbols parameter), argparse raises:
ValueError: unsupported format character '^' (0x5e) at index 129

This was already fixed for CLIArgument in PR aws#9790 but BooleanArgument
was missed. This commit adds the same .replace('%', '%%') escaping to
BooleanArgument.add_to_parser() and adds a test to verify all service
operations with % in documentation work correctly.

Fixes compatibility with Python 3.14+

Author: adev-code

awscli/arguments.py

@@ -593,7 +593,7 @@ def add_to_arg_table(self, argument_table):
     def add_to_parser(self, parser):
         parser.add_argument(
             self.cli_name,
-            help=self.documentation,
+            help=self.documentation.replace('%', '%%'),
             action=self._action,
             default=self._default,
             dest=self._destination,