for automation tests, allow override of TEST_UFSWM for whether to execute tests

[BruceKropp-Raytheon]

Is your feature request related to a problem? Please describe.
In util/weekly_build/06_AppTests.sh there is a check of TEST_UFSWM , = ON or OFF, which controls whether to execute apptests/test_ufswm.sh

if [ "$TEST_UFSWM" == ON ]; then
. $(dirname $0)/apptests/test_ufswm.sh
fi

However, when sourcing the sites/my_machine.sh (e.g. orion.sh), this value is hardcoded as:

TEST_UFSWM=ON

Describe the solution you'd like
Should be change to allow override:

TEST_UFSWM=${TEST_UFSWM:-"ON"}

Additional context
This allows for test execution options to be specified within CICD (Jenkins) jobs.