[2748109647]

Summary

Fixes #4335.

• Precompute literal host patterns when the route predicate is created and use a Set lookup when the route has no URI-template variables.
• Keep ordered matching for routes containing {var} patterns, so the first matching template continues to populate URI variables as before.
• Preserve the configured PathMatcher behavior by using the existing matcher path whenever a custom matcher is set.
• Skip URI-template extraction for literal matches while still merging an empty variable map into the exchange.

Verification

• ./mvnw -pl spring-cloud-gateway-server-webflux -Dtest=HostRoutePredicateFactoryTests test — 11 tests passed.
• Checkstyle reported 0 violations during the Maven validation phase.
• git diff --check — passed.