[BEAM-13601] Don't cache Row types for a schema. (#16427)
[BEAM-13601] Don't cache Row types for a schema. (#16427)

This fixes apache_beam.tools.microbenchmarks_test.MicrobenchmarksTest.test_coders_microbenchmark.

Also separate out the named tuple and row cases as they have
little in common at this point.
apache/beam,apache/beam,robertwb/incubator-beam,robertwb/incubator-beam,robertwb/incubator-beam,chamikaramj/beam,robertwb/incubator-beam,lukecwik/incubator-beam,chamikaramj/beam,apache/beam,apache/beam,chamikaramj/beam,chamikaramj/beam,chamikaramj/beam,chamikaramj/beam,lukecwik/incubator-beam,lukecwik/incubator-beam,lukecwik/incubator-beam,chamikaramj/beam,lukecwik/incubator-beam,robertwb/incubator-beam,robertwb/incubator-beam,lukecwik/incubator-beam,apache/beam,chamikaramj/beam,lukecwik/incubator-beam,chamikaramj/beam,robertwb/incubator-beam,lukecwik/incubator-beam,apache/beam,lukecwik/incubator-beam,apache/beam,robertwb/incubator-beam,apache/beam,robertwb/incubator-beam,lukecwik/incubator-beam,apache/beam,chamikaramj/beam,robertwb/incubator-beam,apache/beam,apache/beam