Fix data_logger timer

[BenediktBurger]

Fixes bugs:

• If you set the trigger to the timer and a timeout, the timer is started before the timeout value is updated, therefore the timer uses the previous timeout value.
• There was no lock around the lists, therefore, while saving a file, the timed trigger (executed in another thread) could add elements to list, enlarging some of the lists, but not all.

This PR modifies the tests to show this scenario (first issue) and fixes the problem.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 87.58%. Comparing base (0ce18cf) to head (5238d1c).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #70 +/- ## ========================================== - Coverage 87.60% 87.58% -0.03% ========================================== Files 36 36 Lines 2888 2899 +11 Branches 348 355 +7 ========================================== + Hits 2530 2539 +9 - Misses 298 300 +2 Partials 60 60 ``` | [Flag](https://app.codecov.io/gh/pymeasure/pyleco/pull/70/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pymeasure) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/pymeasure/pyleco/pull/70/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pymeasure) | `87.58% <100.00%> (-0.03%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pymeasure#carryforward-flags-in-the-pull-request-comment) to find out more.

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