Bring Linux coverage out of bringup (#181280)

Marked as bringup as of #174171. With the new dashboard level flake
suppression, it will no longer take a long time to mark things as flaky.
Also, this seems to be running on every commit now?

.ci.yaml

diff --git a/.ci.yaml b/.ci.yaml
index 747409a..d617453 100644
--- a/.ci.yaml
+++ b/.ci.yaml
@@ -384,8 +384,6 @@
       task_name: analyzer_benchmark
 
   - name: Linux coverage
-    # Because this only runs every 6 commits, it being flaky takes a long time to recover.
-    bringup: true
     presubmit: false
     recipe: flutter/coverage
     timeout: 90