OAA PR filter is very hard to read

[matejak]

The OAA PR job configuration uses a matrix build together with a filter.
The filter is really hard to read:

   !(t_branch=="rhel7-branch" && distributions=="fedora")
&& !(t_branch=="master" && distributions=="rhel7")
&& !(t_branch=="rhel8-branch" && distributions=="rhel7")

What about replacing it with something like

   (t_branch=="rhel7-branch" && distributions=="rhel7")
|| (t_branch=="rhel8-branch" && distributions=="rhel8")
|| (t_branch=="master" && distributions=="fedora")

and in case when master is compatible with rhel8 just add that combination to the condition.

Moreover, I think that the first form works only because the rhel8 label is left out from the matrix.
As the second solution looks obviously better, I have a feeling that I may be missing something.