Incorrect Test Execution Time and Cost Calculation

[tijanastikic]

Describe the bug
Total test execution time and corresponding costs calculated incorrectly when running tests in parallel on Firebase Test Lab.

To Reproduce

Steps to reproduce the behavior:

1. With the setup explained bellow in "Details" section, run gradle command: ./gradlew runFlank
2. Check logs and search for "CostReport" section

Expected behavior

Time displayed in the cost report (therefore the cost should be smaller) should be the same time as needed for test execution

Details:

• Fladle version: "0.17.5"
• Devices config: 4 devices total: '[{"model": "x1q", "version": "29"}, {"model": "a52sxq", "version": "34"}, {"model": "dm3q", "version": "33"}, {"model": "cactus", "version": "27"}]'
• Fladle setup:

Actual behavior

Actual execution time took 4m 20s
Calculated time in cost report 28m