Play: Optimize usages of route

[kciesielski]

Closes #3549

Turns out Play calls DefaultPekkoHttpServerComponents.route on each request, so we shouldn't rebuild routing in that method. Instead, it should return a pre-calculated value.
This isn't a fix to Tapir per se, but to all usages of the Play server we have in standard tests and performance tests.
Performance tests used to show terrible latency/throughput and Tapir code occupying over 90% of all frames registered by the profiler.
After this fix, the latency is dramatically better (see the blue line):

Throughput also reaches great values: ~160k reqs/sec vs 5k before the fix. Tapir code occupies no more than 9% of all profiler frames. There may be still some possible optimizations in the late 0.999s of latency to reach values closer to the vanilla server under very heavy load, but at this point I don't see them as necessary.

[adamw]

Nice :)