[rules engine] `Default` rule cleans header

[0xf104a]

Describe the bug When Default rule is used the headers are cleaned, and only Connection is sent. Thise leads to lack of Content-length header and so browser failing to finalize request correctly.

To Reproduce In config apply Default rule to some route. Request this route through any client.

Expected behavior The header MUST NOT be cleaned when using Default rule

OS & client (please complete the following information):

• OS: Any
• Client: Any
• Client options(if applicable): N/A
• Version: Any