fix(router): forward the matched path when nginx normalizes the request uri

[shreemaan-abhishek]

Description

Routes are matched on the normalized $uri: Nginx percent-decodes the path, resolves dot segments (including encoded ones such as ..%2F and %2e%2e) and merges consecutive slashes. With $upstream_uri left empty, proxy_pass then forwards the original request line. When normalization changed the path, the upstream receives a different path from the one the route was matched on. For example, /admin/..%2Fapi/x matches a route for /api/*, but the upstream receives /admin/..%2Fapi/x.

This PR forwards the path the route was matched on whenever Nginx did more than percent-decode it:

• In http_access_phase, if a plain percent-decode of the raw request path differs from $uri, $upstream_uri is set to the re-encoded $uri plus the original query string. This reuses the same equivalence check as match_uri_encoded_slash.
• Requests that only need percent-decoding still forward the original request line unchanged, so %2F inside path parameters and other encodings are preserved.
• Plugins that set $upstream_uri later (such as proxy-rewrite) still take precedence.
• normalize_uri_like_servlet is left as is, since it already forwards the normalized path.

Behavior change

Upstreams that received raw dot segments or consecutive slashes in the request path (/a/../b, /a/%2e%2e/b, /a//b) now receive the normalized path (/b, /a/b). Requests without these are unaffected.

Which issue(s) this PR fixes:

Fixes #

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible (If not, please discuss on the APISIX mailing list first)