Use `HttpExecutionStrategies.difference` in jersey router

We have a modified implementation of `HttpExecutionStrategies.difference` function in `http-router-jersey`: https://github.com/apple/servicetalk/blob/464554ad984bc4897e7ba72e54a2ac0f12a9ecd9/servicetalk-http-router-jersey/src/main/java/io/servicetalk/http/router/jersey/EndpointEnhancingRequestFilter.java#L487-L508

We introduced it #682 to improve accuracy according to jersey router specifics. However, we should reconsider this approach and consolidate the `difference` logic in one place, because there should be no difference between router implementations. See discussion on gRPC router implementation: https://github.com/apple/servicetalk/pull/912#discussion_r364392328

Start in servicetalk-http-router-jersey/src/main/java/io/servicetalk/http/router/jersey/EndpointEnhancingRequestFilter.java around the modified difference implementation, then read HttpExecutionStrategies.difference and the gRPC router discussion in pull request 912. Done means the Jersey router uses the consolidated difference logic without router-specific divergence.

Written by the indexing model from the issue text.