Android: Restore searching PATH for executables

Since !5357 (merged), we turn off CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH. This breaks find_program searching 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)
Backport: release
Topic-rename: android-PATH