tests: kernel: pipe: second part of testcases to improve pipes coverage

Added test_pipe_get_large to cover branches in both k_pipe_put and
k_pipe_get. Added trivial testcases in test_pipe_avail_no_buffer to
cover trivial branches for k_pipe_read_avail and k_pipe_write_avail.
This is the second patch as the continuation of #31037.

Signed-off-by: Shihao Shen <shihao.shen@intel.com>