Crash if profile is misconfigured

[tsloughter]

I missed putting [] around the configuration of a profile so it was just a tuple. This caused rebar3 to crash when it tried to use proplists later on and just give the message about running with DIAGNOSTIC=1 instead of an error message. Stacktrace:

===> Stack trace to the error location:
[{proplists,get_value,
     [erl_opts,
      {deps,
          [{eqwalizer_support,
               {git_subdir,"https://github.com/whatsapp/eqwalizer.git",
                   {branch,"main"},
                   "eqwalizer_support"}}]},
      []],
     [{file,"proplists.erl"},{line,214}]},
 {rebar3,test_state,1,
     [{file,"/home/runner/work/rebar3/rebar3/apps/rebar/src/rebar3.erl"},
      {line,477}]},

[tsloughter]

Also, I was running just rebar3 compile so not using the test profile. Seems weird to build the test profile even when it isn't used. I'll look into why we do that... and a fix for this.