[FEATURE] three minor fixes to consider

[noelmcloughlin]

Is your feature request related to a problem?

Describe the solution you'd like

General issue

• The mongod.sh file contains superfluous {} line

bobby@work kubernetes % cat /etc/default/mongod.sh 
########################################################################
# File managed by Salt at <salt://mongodb/files/default/environ.sh.jinja>.
# Your changes may be overwritten.
########################################################################

export PATH=${PATH}:/usr/local/mongodb/mongod-4.2.6
{}

On MacOS-

• The formula should manage mongod.sh in /etc/defaults/ not /etc/default/

          ID: mongodb-config-install-mongod-environ_file
    Function: file.managed
        Name: /etc/default/mongod.sh
      Result: True
     Comment: File /etc/default/mongod.sh is in the correct state
     Started: 20:43:29.766874
    Duration: 22.894 ms

• There should be symlinks from /usr/local/mongo-xxxx/bin/cmd to /usr/local/bin/cmd

bobby@work % ls /usr/local/mongodb/mongod-4.2.6/bin 
bsondump	mongo		mongodump	mongofiles	mongoreplay	mongos		mongotop
install_compass	mongod		mongoexport	mongoimport	mongorestore	mongostat

Describe alternatives you've considered

Additional context