[TSVB] Add more functional tests

[stratoula]

Describe the feature:
We want to add more functional tests for our TSVB plugin.

Some scenarios that will be useful to test are:

• Timeseries: [TSVB] Add more functional tests for Timeseries #106100

1. Test actual chart data (elastic-charts offers this ability now) (for example with an Avg aggregation, percentile aggregation)
2. Test group by terms (chart data and legends, also colors applied)
3. Test group by filters (chart data, legend, add a custom name, change the color, see if it is applied)
4. Add a new series, check that the new series is rendered, change the type to bar, test that a bar is rendered
5. Override the index pattern, add another one, are the data displayed correctly (do it without selecting a timefield)
6. Filter the data, are they filtered correctly?
7. Change the interval from auto to another value, test the chart data
8. Test the Panel filter
9. Test annotations
10. Test annotations with runtime fields! (after this [TSVB] annotations support runtime fields #104287 is merged)

Note: Testing actual annotations data requires extending debug data in elastic-charts (elastic/elastic-charts#1260)

• Metric: [TSVB] Top_hit supports runtime fields #103401

1. Test the entire timerange mode
2. Test the last value mode
3. Add some color rules and check is they are applied
4. Test the index pattern and the string mode

• TopN and Gauge: [TSVB] Add more functional tests for Gauge and TopN #105361

1. Test style and color rules
2. Change the series color and check if it is applied
3. Test the entire timerange mode
4. Test the last value mode

• Table [TSVB] Add more functional tests for Table #105060

1. Test the entire timerange mode
2. Test the last value mode
3. Create a test for the math agg
4. Add more tests for various aggregations

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[DianaDerevyankina]

Waiting for elastic charts debug data to be extended with annotations data to add some tests for annotations actual data