Remove conflicting NoExecPaths and ExecPaths settings

Remove conflicting NoExecPaths and ExecPaths settings

From testing, ExecPaths setting appears to override the
TemporaryFileSystem setting. When both NoExecPaths=/ and
TemporaryFileSystem=/ are used, the entire filesystem remains available
in the sandbox.

This might be a bug with systemd since it doesn't appear to be
documented (as of version 257).

This isn't much of an issue since NoExecPaths didn't add much in the
first place, since it's still possible to use any executable
interpreters to load non-executable files, and /lib/ld-linux.so.2 is an
interpreter that allows executing any ELF binaries, and must be marked
executable for any binary to run in the first place. So an attacker
could always work around it fairly easily.