fix build_docker.sh files for flag issue: -a vs -p

[marvin-better]

Issue

The 3 existing (identical) docker_build.sh files all had help text describing both an -a and a -p flag for setting the project name, but only a -a was allowed.

Fix

This will allow either -a or -p to set the project name, to be compatible with existing uses and the help text.
Note that I did omit the -a from the help text: it now only prints the -p option.

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