Add warning on begin if using test clock

[LowriJenkins]

Description of work

Adds a warning to the begin() function if the scientists are using the test clock and are not in simulated DAE

To test

ISISComputingGroup/IBEX#8725

Acceptance criteria

• When begining a run from a script if the dae is not simulated and the test clock is active, a warning is printed telling the user that the test clock is active and how to change there timing source.

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Code Review

• Is the code of an acceptable quality?
• Are there unit tests in place? Are the unit tests small and test the a class in isolation?
• Have the changes been documented in the release notes. If so, do they describe the changes appropriately?

Functional Tests

• Do changes function as described? Add comments below that describe the tests performed.
• How do the changes handle unexpected situations, e.g. bad input?
• Has developer documentation been updated if required?