analytics: Migrate models' id columns to bigint.

This helps prevent wraparound on exceedingly large and old installs,
particularly Zulip Cloud.  These are relatively simple migrations
since they are not referenced by any other tables; however, they are
quite large, and are actively used from Django by running servers,
making this not a migration which is possible to run without stopping
the server.

Use the escape hatch in the previous commit to temporarily pause
analytics writes while the migration happens.  This should make the
migration transparent to users, at the small cost of an artificial dip
in statistics (specifically, to push notification counts, and unread
message counts) while the migration runs.

analytics/migrations/0020_alter_installationcount_id_alter_realmcount_id_and_more.py

@@ -0,0 +1,40 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    atomic = False
+
+    dependencies = [
+        ("analytics", "0019_remove_unused_counts"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="installationcount",
+            name="id",
+            field=models.BigAutoField(
+                auto_created=True, primary_key=True, serialize=False, verbose_name="ID"
+            ),
+        ),
+        migrations.AlterField(
+            model_name="realmcount",
+            name="id",
+            field=models.BigAutoField(
+                auto_created=True, primary_key=True, serialize=False, verbose_name="ID"
+            ),
+        ),
+        migrations.AlterField(
+            model_name="streamcount",
+            name="id",
+            field=models.BigAutoField(
+                auto_created=True, primary_key=True, serialize=False, verbose_name="ID"
+            ),
+        ),
+        migrations.AlterField(
+            model_name="usercount",
+            name="id",
+            field=models.BigAutoField(
+                auto_created=True, primary_key=True, serialize=False, verbose_name="ID"
+            ),
+        ),
+    ]

analytics/models.py

@@ -38,6 +38,9 @@ class BaseCount(models.Model):
     # Note: When inheriting from BaseCount, you may want to rearrange
     # the order of the columns in the migration to make sure they
     # match how you'd like the table to be arranged.
+    id = models.BigAutoField(
+        auto_created=True, primary_key=True, serialize=False, verbose_name="ID"
+    )
     property = models.CharField(max_length=32)
     subgroup = models.CharField(max_length=16, null=True)
     end_time = models.DateTimeField()

zilencer/migrations/0062_alter_remoteinstallationcount_id_and_more.py

@@ -0,0 +1,26 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    atomic = False
+
+    dependencies = [
+        ("zilencer", "0061_clean_count_tables"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="remoteinstallationcount",
+            name="id",
+            field=models.BigAutoField(
+                auto_created=True, primary_key=True, serialize=False, verbose_name="ID"
+            ),
+        ),
+        migrations.AlterField(
+            model_name="remoterealmcount",
+            name="id",
+            field=models.BigAutoField(
+                auto_created=True, primary_key=True, serialize=False, verbose_name="ID"
+            ),
+        ),
+    ]