refactor(webdriver): simplify direct connect capabilities check and logging

[Dor-bl]

Description

Simplifies the direct connect capabilities validation and debug message construction in _update_command_executor:

• Replaces iterative string concatenation with an idiomatic generator expression (' '.join(...)).
• Passes self.caps directly to issubset() instead of creating an intermediate set(self.caps), querying the dictionary keys directly.