Bug 1788968 - Rename nightly beta cron for perftest to daily. r=sparky, a=test-only DONTBUILD

Renaming `nightly` to `daily` is intended for avoiding confusion with Nightly builds and better reflect what we are doing with these performance tests.

.cron.yml

@@ -231,11 +231,11 @@ jobs:
           - {weekday: 'Monday', hour: 8, minute: 0}
           - {weekday: 'Thursday', hour: 8, minute: 0}
 
-    - name: nightly-beta-perf
+    - name: daily-beta-perf
       job:
           type: decision-task
-          treeherder-symbol: n-perf
-          target-tasks-method: nightly_beta_perf
+          treeherder-symbol: d-perf
+          target-tasks-method: daily_beta_perf
           include-push-tasks: true
       run-on-projects:
           - mozilla-beta

taskcluster/gecko_taskgraph/target_tasks.py

@@ -1157,10 +1157,10 @@ def target_tasks_nothing(full_task_graph, parameters, graph_config):
     return []
 
 
-@_target_task("nightly_beta_perf")
-def target_tasks_nightly_beta_perf(full_task_graph, parameters, graph_config):
+@_target_task("daily_beta_perf")
+def target_tasks_daily_beta_perf(full_task_graph, parameters, graph_config):
     """
-    Select performance tests on the beta branch to be run nightly
+    Select performance tests on the beta branch to be run daily
     """
 
     def filter(task):