jobs: increase the test timeout

This package seems to timeout every night in our stress build, both
under race and without it. Under test, without stress, it took 200s for
me on a fast machine. The current timeout is 300s - which seems too
tight. This patch increases it to 900.
Without race and without stress, the pkg runs in about 30s for me. But
I'm not sure I'm running it with the `deadlock` build tag, like CI is.
Some of the failures below are from no-race stress builds.

Closes cockroachdb#92188
Closes cockroachdb#92191
Closes cockroachdb#92110
Closes cockroachdb#92111
Closes cockroachdb#92046

Release note: None
Epic: None

pkg/jobs/BUILD.bazel

@@ -78,7 +78,7 @@ go_library(
 
 go_test(
     name = "jobs_test",
-    size = "medium",
+    size = "large",
     srcs = [
         "delegate_control_test.go",
         "executor_impl_test.go",
@@ -93,7 +93,7 @@ go_test(
         "scheduled_job_test.go",
         "testutils_test.go",
     ],
-    args = ["-test.timeout=295s"],
+    args = ["-test.timeout=895s"],
     embed = [":jobs"],
     shard_count = 16,
     deps = [