Scrub pluggable transport file paths from log messages

Tor logs the file path of the pluggable transport binaries. On desktop platforms these paths might contain sensitive data such as user names that shouldn't be logged.

Example:

05-07 09:59:54.191 I/TorWrapper: NOTICE Managed proxy \"/data/app/~~AN_deXWsWzeDVEaQKlwywQ==/org.briarproject.briar.android-PhR0ETCE4O5LGAHjfWxfEw==/lib/arm64/libsnowflake.so\": connected