In the Test Execution issue, the filter by assignee only returns the Test Runs whose assignee is the user assigned to the Test Execution issue (also, "Assignee" filter should be renamed to "TestRun Assignee")

Short Description: In the Test Execution issue, the filter by assignee only returns the Test Runs whose assignee is the user assigned to the Test Execution issue (also, "Assignee filter should be renamed to "TestRun Assignee").

Steps to Reproduce:

1 - Navigate to a Test Execution issue with Tests in it

2 - Assign the Test Execution issue to user A

3 - Pick come Tests, in the Tests section of the Test Execution, and click in the "..." icon

4 - Assign some of them to user A and some others to user B

5 - To the columns of the section add also the Test Run Assignee

6 - Now, filter the section by assignee B and then by assignee A

7 - Now, change the assignee of the Test Execution to B and repeat step 6

Actual Result: When filtering by assignee B no results will be displayed, while filtering by assignee A, the respective results are displayed. After step B, the opposite will be displayed

Expected Result: It should return all respective test run assignee when filtering by assignee