Revert "ci: raise three unit shard job timeouts to satisfy the startup safety gate"

This reverts commit b71b574af4.

.github/workflows/test-unit.yml

@@ -211,7 +211,7 @@ jobs:
             workers: 2
             reruns: 2
             timeout-minutes: 20
-            job-timeout-minutes: 60
+            job-timeout-minutes: 55
 
           - shard: proxy-extras
             artifact-name: proxy-extras
@@ -219,7 +219,7 @@ jobs:
             workers: 2
             reruns: 2
             timeout-minutes: 20
-            job-timeout-minutes: 60
+            job-timeout-minutes: 55
 
           - shard: enterprise-package
             artifact-name: enterprise-package
@@ -227,7 +227,7 @@ jobs:
             workers: 4
             reruns: 2
             timeout-minutes: 20
-            job-timeout-minutes: 60
+            job-timeout-minutes: 55
 
           - shard: responses-caching-types
             artifact-name: responses-caching-types