[Autofill] De-template-ify some crowdsourcing matchers

This CL aims to simplify the matchers in
autofill_crowdsourcing_encoding_unittest.cc in the following way:

- It replaces the SerializesSameAs() template with two overloads for
  AutofillPageQueryRequest and AutofillUploadContents.
  That makes it easier to add additional equality checks to the
  matchers for debugging. That's useful because debugging equality
  checks on the serialized representation of the protobufs is tedious.

- It removes the matcher ElementsSerializeSameAs().
  ElementsSerializeSameAs(x) is now ElementsAre(SerializesSameAs(x)).
  That makes it easier to see that the function under test returns a
  std::vector.

- It removes the matchers UnorderedElementsSerializeSameAs().
  It's now inlined at the single callsite.

Bug: 40100455
Change-Id: I71dafa87f79ac380eacda2a3521c03ab4eccd724
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6388217
Reviewed-by: Jan Keitel <jkeitel@google.com>
Commit-Queue: Christoph Schwering <schwering@google.com>
Cr-Commit-Position: refs/heads/main@{#1437218}