chore(rc,profile,aliases,completion,libs,functions): Remove shebangs from sourced files

These files are always sourced (never executed directly), so the
#!/bin/bash shebang is inert and misleading. Drop it consistently
across rc.d/*, profile.d/*, and aliases.d/*.

aliases.d/system

@@ -1,5 +1,3 @@
-#!/bin/bash
-
 # System tools
 if [ -f /sbin/ifconfig ] && [ -x /sbin/ifconfig ]; then alias ifconfig='/sbin/ifconfig'; fi
 if [ -f /sbin/ip ] && [ -x /sbin/ip ]; then alias ip='/sbin/ip'; fi