Use aquery results to determine if a file should be executable

Now that aquery includes this information.

Also added rm -f $out to some rules, because since they write files
by shell redirection, if the file existed before and was executable,
they wouldn't make the file non-executable and visa versa.

Fixes: 297366783
Test: m bazel_sandwich
Change-Id: Ie5b6c4275b162601f51deaec9912eea4be16988d