Fix / refine regression detection and generation

[r-c-n]

When checking for regressions, the regression_tracker service is not taking into account all the required node fields, so it's detecting and creating them based on incomplete data (focusing only on the kernel version), which leads to incorrect results. For example:

Regression 65c0dc956c0c48387d459105 points to a failed node that ran on a different platform than the passed node, so that's not really a regression.

To be considered a regression the only difference should be the kernel version, but all the other test parameters (platform, compiler setup, defconfig and other build attributes) should be the same.

[r-c-n]

Done in #447, although the intended solution is to have kernelci/kernelci-core#2378 and #444 merged eventually