chore: Remove project template endpoints

[markstory]

We didn't ever finish off this feature and it has languished for a many months. With the OTLP taking a different route, I don't see us using ProjectTemplates any time soon.

Remove the endpoints and tests as a first step, next I'll remove the models.

[sentry]

Bug: The ProjectOptionsTests test class calls the create_project_template() method in its setUp() function, but this method has been removed from the test utility classes, which will cause an AttributeError.
_{Severity: CRITICAL}

Suggested Fix

The ProjectOptionsTests class and its usage of create_project_template() should be removed or updated. Since the functionality related to project templates is being removed, the associated tests are likely no longer necessary and should be deleted.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: src/sentry/testutils/factories.py#L587-L592

Potential issue: The pull request removes the test helper method
`create_project_template()` from `src/sentry/testutils/factories.py` and
`src/sentry/testutils/fixtures.py`. However, the test class `ProjectOptionsTests` in
`tests/sentry/models/test_project.py` still invokes this method within its `setUp()`
function. Because the test class inherits from `TestCase`, which uses the `Fixtures`
class, the call to the now-nonexistent `self.create_project_template()` will raise an
`AttributeError`. This will cause all tests within the `ProjectOptionsTests` suite to
fail during setup, preventing them from running.

_{Did we get this right? 👍 / 👎 to inform future reviews.}

[github-actions]

🚨 Warning: This pull request contains Frontend and Backend changes!

It's discouraged to make changes to Sentry's Frontend and Backend in a single pull request. The Frontend and Backend are not atomically deployed. If the changes are interdependent of each other, they must be separated into two pull requests and be made forward or backwards compatible, such that the Backend or Frontend can be safely deployed independently.

Have questions? Please ask in the #discuss-dev-infra channel.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

[github-actions]

Backend Test Failures

Failures on ec1b6c5 in this run:

tests/sentry/models/test_project.py::ProjectOptionsTests::test_get_option__without_template — log

tests/sentry/models/test_project.py:654: in setUp
    self.project_template = self.create_project_template(organization=self.project.organization)
E   AttributeError: 'ProjectOptionsTests' object has no attribute 'create_project_template'. Did you mean: 'create_project_rule'?

tests/sentry/test_devimports.py::test_startup_imports[sentry] — log

tests/sentry/test_devimports.py:122: in test_startup_imports
    validate_package(pkg, EXCLUDED, XFAIL)
tests/sentry/test_devimports.py:117: in validate_package
    raise AssertionError(ret.stdout)
E   AssertionError: error importing sentry.api.endpoints.project_templates_index:
E   
E   Traceback (most recent call last):
E     File "<string>", line 35, in <module>
E       __import__(name)
E       ~~~~~~~~~~^^^^^^
E     File "<string>", line 15, in _import
E       return orig(name, globals=globals, locals=locals, fromlist=fromlist, level=level)
E     File "/home/runner/work/sentry/sentry/src/sentry/api/endpoints/project_templates_index.py", line 13, in <module>
E       from sentry.api.serializers.models.project_template import (
E       ...<2 lines>...
E       )
E     File "<string>", line 15, in _import
E       return orig(name, globals=globals, locals=locals, fromlist=fromlist, level=level)
E   ModuleNotFoundError: No module named 'sentry.api.serializers.models.project_template'

tests/sentry/models/test_project.py::ProjectOptionsTests::test_get_option — log

tests/sentry/models/test_project.py:654: in setUp
    self.project_template = self.create_project_template(organization=self.project.organization)
E   AttributeError: 'ProjectOptionsTests' object has no attribute 'create_project_template'. Did you mean: 'create_project_rule'?

tests/sentry/models/test_project.py::ProjectOptionsTests::test_get_option__override_template — log

tests/sentry/models/test_project.py:654: in setUp
    self.project_template = self.create_project_template(organization=self.project.organization)
E   AttributeError: 'ProjectOptionsTests' object has no attribute 'create_project_template'. Did you mean: 'create_project_rule'?

tests/sentry/models/test_project.py::ProjectOptionsTests::test_get_option__without_template_and_value — log

tests/sentry/models/test_project.py:654: in setUp
    self.project_template = self.create_project_template(organization=self.project.organization)
E   AttributeError: 'ProjectOptionsTests' object has no attribute 'create_project_template'. Did you mean: 'create_project_rule'?