remove bionic-compile-time-tests-g++

make checkbuild gives the following error:
bionic/tests/fortify_filecheck_diagnostics_test.cpp:1:0: error: unknown value 'cortex-a55' for -mcpu

The error is because we have a clang to support the new architecture,
but not a corresponding GCC. It is not trivial to filter out an invalid
CPU, and since there is no platform code built with GCC any more, its
better to remove bionic-compile-time-tests-g++

Bug: 74404306
Change-Id: I6aa181c652abeef782fec6380dfadd066140b8b9