Exclude `removed` packages from pages

The packages table has a column called removed. It would be nice to stop viewing results for removed packages in the following pages/results:

/status (currently the graph keeps on including very old results including failures from running the test after removal)
/status/alerts ; no actionable issues
/status/failing ; no actionable failures
/status/platform-specific-issues/ ; no actionable issues

I propose we keep showing:

/ and /packages/* ; (although I considered hiding my accidental test of package 886648 this way)
/data/feeds/