Running ops.testing or ops.scenario tests fails when a charm uses the DatabaseRequires class

When using the `relation_aliases` option dynamic events are created. For some reason unlike other events these seem to persist across test invocations and cause event type duplication errors. I'm raising this against this interface as it's the only place I see this issue but it's possible the root cause of the bug is in ops.

## Steps to reproduce
Run a ops.scenario (or ops.testing) `pytest` test which uses `DatabaseRequires` with the `relations_aliases` option. For example:

```python
import pytest
from scenario import State, Context, Container, Relation
from ops.charm import CharmBase
from ops.model import UnknownStatus

from charms.data_platform_libs.v0.database_requires import (
DatabaseRequires,
DatabaseCreatedEvent,
)

class ApplicationCharm(CharmBase):
def __init__(self, *args):
super().__init__(*args)
self.database = DatabaseRequires(
self,
relation_name="database",
database_name="database",
relations_aliases=["an_alias"],
)
self.framework.observe(
self.database.on.database_created, self._on_database_created
)

def _on_database_created(self, event: DatabaseCreatedEvent) -> None:
self.status.set(ActiveStatus("received database credentials"))

@pytest.mark.parametrize("leader", (True, False))
def test_charm_no_deps(leader):
metadata = {
"name": "myapp",
"version": "3",
"subordinate": False,
"requires": {"database": {"interface": "mysql_client", "limit": 1}},
}
state = State(
leader=leader,
config={},
containers=[],
relations=[
Relation(
endpoint="database",
interface="mysql_client",
remote_app_name="mysql",
local_unit_data={},
remote_app_data={},
)
],
)
ctxt = Context(charm_type=ApplicationCharm, meta=metadata)
out = ctxt.run("config-changed", state)
assert out.unit_status == UnknownStatus()
```

## Expected behavior
```
2 passed in Xs
```
## Actual behavior
```
...
E RuntimeError: unable to define an event with event_kind that overlaps with an existing type attribute: an_alias_database_created
...
1 failed, 1 passed in Xs
```
## Versions
```
ops: 2.4.1
ops-scenario: 4.0.4
charms.data_platform_libs.v0.database_requires:
LIBID = "0241e088ffa9440fb4e3126349b2fb62"
LIBAPI = 0
LIBPATCH = 4
```