feat: DIA-1064: Get all / sample tasks for prompts task list (#5950)

### PR fulfills these requirements
- [x] Commit message(s) and PR title follows the format
`[fix|feat|ci|chore|doc]: TICKET-ID: Short description of change made`
ex. `fix: DEV-XXXX: Removed inconsistent code usage causing intermittent
errors`
- [x] Tests for the changes have been added/updated (for bug
fixes/features)
- [ ] Docs have been added/updated (for bug fixes/features)
- [x] Best efforts were made to ensure docs/code are concise and
coherent (checked for spelling/grammatical errors, commented out code,
debug logs etc.)
- [x] Self-reviewed and ran all changes on a local instance (for bug
fixes/features)



#### Change has impacts in these area(s)
_(check all that apply)_
- [ ] Product design
- [ ] Backend (Database)
- [x] Backend (API)
- [ ] Frontend



### Describe the reason for change
_(link to issue, supportive screenshots etc.)_



#### What does this fix?
_(if this is a bug fix)_



#### What is the new behavior?
_(if this is a breaking or feature change)_



#### What is the current behavior?
_(if this is a breaking or feature change)_



#### What libraries were added/updated?
_(list all with version changes)_



#### Does this change affect performance?
_(if so describe the impacts positive or negative)_



#### Does this change affect security?
_(if so describe the impacts positive or negative)_



#### What alternative approaches were there?
_(briefly list any if applicable)_



#### What feature flags were used to cover this change?
_(briefly list any if applicable)_



### Does this PR introduce a breaking change?
_(check only one)_
- [ ] Yes, and covered entirely by feature flag(s)
- [ ] Yes, and covered partially by feature flag(s)
- [ ] No
- [ ] Not sure (briefly explain the situation below)



### What level of testing was included in the change?
_(check all that apply)_
- [ ] e2e
- [ ] integration
- [ ] unit



### Which logical domain(s) does this change affect?
_(for bug fixes/features, be as precise as possible. ex. Authentication,
Annotation History, Review Stream etc.)_

label_studio/ml_models/migrations/0006_alter_modelrun_project_subset.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.23 on 2024-06-06 22:25
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('ml_models', '0005_auto_20240319_1738'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='modelrun',
+            name='project_subset',
+            field=models.CharField(choices=[('All', 'All'), ('HasGT', 'HasGT'), ('Sample', 'Sample')], default='HasGT', max_length=255),
+        ),
+    ]

label_studio/ml_models/models.py

@@ -110,6 +110,7 @@ class ModelRun(models.Model):
     class ProjectSubset(models.TextChoices):
         ALL = 'All', _('All')
         HASGT = 'HasGT', _('HasGT')
+        SAMPLE = 'Sample', _('Sample')
 
     class FileType(models.TextChoices):
         INPUT = 'Input', _('Input')