tests: samples: Add targetted platform_excludes for intel_adsp_cavs15

This platform has a tiny handful of remaining tests that fail.  We
will track them as issues, but let's exclude them from integration
testing to allow full runs to complete.  Often a hung device in one
test will break an entire twister run.

Tests with known (and tracked) failures:

  samples/application_development/external_lib
  samples/posix/eventfd
  samples/userspace/hello_world_user
  tests/kernel/fatal/message_capture
  tests/net/socket/socketpair
  tests/portability/cmsis_rtos_v2

These tests never fail in isolated testing, but are reliable timeouts
when run in sequence in a big twister run.  It's possible that the bug
here may be in twister or the flash/serial scripts:

  tests/crypto/tinycrypt
  tests/subsys/logging/log_immediate
  tests/subsys/logging/log_output

See: #32836

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>