TMSS-1711: Fixed failing tests. Updated error msg.

...ss_webapp/src/__mocks__/observing_strategy_templates.json

...src/__mocks__/observing_strategy_templates_test_data.json

...SS/frontend/tmss_webapp/src/__mocks__/task_templates.json

...SS/frontend/tmss_webapp/src/routes/Scheduling/Stations.js

...frontend/tmss_webapp/src/routes/Scheduling/create.test.js

...MSS/frontend/tmss_webapp/src/services/schedule.service.js

SAS/TMSS/frontend/tmss_webapp/src/utils/validator.js