Mitigate test saturation of runtime logs

[josh-chamberlain]

Context

• Related to Log filtering data-sources-app#937

Fixes to consider

• Use log filtering to exclude tests by adding a header like X-Test-Run: true to the requests in playwright, and then filtering those out in data-sources-app (or grouping them aggressively)
• Use explicit worker counts
• Use globalSetup and storageState to share browser contexts between workers