Android: Restore searching PATH for executables
Since !5357 (merged), we turn off
CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH. This breaks
PATH for host executables. Fortunately, the setting turns out not to be necessary, perhaps since !5479 (merged). Without it, none of NDK tests fail, so remove it to restore pre-3.20 behavior.
Fixes: #22634 (closed)