chore: fix incorrect number of routing rule stringer

[mzz2017]

Background

Before the fix:

[Jun 10 14:26:46] DEBUG rule: ip([n = 219214]) && l4proto([n = 219215]) -> proxy
[Jun 10 14:26:46] DEBUG         ip() -> <AND>
[Jun 10 14:26:46] DEBUG         l4proto() -> proxy

After the fix:

[Jun 10 14:37:05] DEBUG rule: ip([n = 219214]) && l4proto([n = 1]) -> proxy
[Jun 10 14:37:05] DEBUG         ip() -> <AND>
[Jun 10 14:37:05] DEBUG         l4proto() -> proxy

This problem is caused by the incorrect accumulation of n within the same rule.

This problem only impacts showing.

Checklist

• The Pull Request has been fully tested

Full changelog

• Remove accumulation of n.