Match path before Content-Type in GraphQlRequestPredicates

[MarcoKunze-CPE]

Fixes #1485

The GraphQL route predicates evaluate the request path last, after the method, Content-Type and Accept checks:

return httpMethodMatch(request, HttpMethod.POST)
        && contentTypeMatch(request, this.contentTypes)
        && acceptMatch(request, this.acceptedMediaTypes)
        && pathMatch(request, this.pattern);

Since #1145, contentTypeMatch throws UnsupportedMediaTypeStatusException for an unparseable Content-Type. Because RouterFunctionMapping evaluates the predicate during handler lookup for every request, any POST anywhere in the application with a malformed Content-Type is answered 415 — even when it does not target the GraphQL endpoint at all (details and a real-world failure mode with Vaadin heartbeats in #1485).

This change evaluates pathMatch first, so requests to other paths are never affected by Content-Type or Accept parsing. The deliberate 415 from #1145 is unchanged for requests genuinely aimed at the GraphQL path — the existing shouldRejectRequestWithInvalidContentType test still passes. Applied to both the WebMvc and the WebFlux predicate variants, with a regression test each (shouldNotRejectRequestWithInvalidContentTypeOnDifferentPath, red against the previous ordering with exactly the UnsupportedMediaTypeStatusException, green with this change; all 40 tests in both GraphQlRequestPredicatesTests classes pass).

[MarcoKunze-CPE]

Transparency note: this was researched and written by an AI coding assistant (Claude) operating on my account, after we diagnosed the failure mode in our production stack. Please review it with the appropriate scrutiny, and feel free to close it if it is not relevant or does not match the project's design intent. One known caveat we leave to the team's judgement: with the path matched first, pathMatch's MATCHING_PATTERN_ATTRIBUTE side effect can now also occur for requests that fail the subsequent method/Content-Type/Accept checks (e.g. GET /graphql) — if the attribute must only be set on a full route match, a narrower fix may be preferable.