Revert "expose SlavedProfileStore to ClientReaderSlavedStore (#5200)"

This reverts commit ce5bcef.

This caused:

```
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/local/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/home/synapse/src/synapse/app/client_reader.py", line 32, in <module>
    from synapse.replication.slave.storage import SlavedProfileStore
ImportError: cannot import name 'SlavedProfileStore' from 'synapse.replication.slave.storage' (/home/synapse/src/synapse/replication/slave/storage/__init__.py)
error starting synapse.app.client_reader('/home/synapse/config/workers/client_reader.yaml') (exit code: 1); see above for logs
```

synapse/app/client_reader.py

@@ -29,7 +29,6 @@
 from synapse.http.site import SynapseSite
 from synapse.metrics import RegistryProxy
 from synapse.metrics.resource import METRICS_PREFIX, MetricsResource
-from synapse.replication.slave.storage import SlavedProfileStore
 from synapse.replication.slave.storage._base import BaseSlavedStore
 from synapse.replication.slave.storage.account_data import SlavedAccountDataStore
 from synapse.replication.slave.storage.appservice import SlavedApplicationServiceStore
@@ -84,7 +83,6 @@ class ClientReaderSlavedStore(
     SlavedTransactionStore,
     SlavedClientIpStore,
     BaseSlavedStore,
-    SlavedProfileStore,
 ):
     pass