Backport: test contract fixes

[linh2931]

EOSIO/eos#9114

Need to verify with Mandel CDT if those deprecated headers in eosio.cdt v1.7.x were removed. If they were removed, it is not possible to build EOSIO with -DEOSIO_COMPILE_TEST_CONTRACTS=true. A big task.

[oschwaldp-oci]

Also required backport of: EOSIO/eos#9390

Resolves issue with StaticArray test by removing test:

 * Reason:
 * it was working in c++14 but fails in c++17 due to braces elision
 * 
 * Details:
 * In c++17 StaticArray can be constructed with {10,20} or {{10,20}} using braces elision feature
 * boost::pfr::for_each_field chosing constructor with maximum parameters available
 * which is 2 in commented out example and then it fails to compile here
 *    <skipped>/include/boost/pfr/detail/core17_generated.hpp:51:9: error: type 'StaticArray'
 *    decomposes into 1 elements, but 2 names were provided
 *    auto& [a,b] = val;
 * this issue is known by author of the library and is not resolved yet:
 * https://github.com/apolukhin/magic_get/issues/16