TC_BOOLCFG_3_1 fix test step description

[r-recchia]

Fix test descriptions in https://github.com/project-chip/connectedhomeip/blob/master/src/python_testing/TC_BOOLCFG_3_1.py

Check with https://github.com/CHIP-Specifications/chip-test-plans/blob/master/src/cluster/boolean_state_configuration.adoc#512-tc-boolcfg-31-sensitivitylevel-with-dut_server

Ensure test plan makes sense