Fail if local Postgres cluster fails to start

It was a while since the last time I used my linux box to develop
EdgeDB. Since then we've upgraded Postgres to 14.2 from 13. My
`localdev` directory was created by Postgres 13, so naturally
Postgres 14 wouldn't start with it.

`edb server`, however, was silently hanging without printing any error
messages. Fix this by actively checking if the Postgres process is still
alive while trying to establish the first connection to the cluster.

Once this was fixed, the following (expected) messages appeared in our
stderr:

  CRITICAL postgres: database files are incompatible with server
  INFO postgres: The data directory was initialized by PostgreSQL
       version 13, which is not compatible with this version 14.2.

edb/server/pgcluster.py

@@ -28,7 +28,6 @@
 import shlex
 import shutil
 import textwrap
-import time
 import urllib.parse
 
 import asyncpg
@@ -664,7 +663,19 @@ async def _test_connection(self, timeout: int = 60) -> str:
             try:
                 conn_addr = self._get_connection_addr()
             except PostgresPidFileNotReadyError:
-                time.sleep(sleep_time)
+                try:
+                    assert self._daemon_process is not None
+                    code = await asyncio.wait_for(
+                        self._daemon_process.wait(),
+                        sleep_time
+                    )
+                except asyncio.TimeoutError:
+                    # means that the postgres process is still alive
+                    pass
+                else:
+                    # the postgres process has exited prematurely
+                    raise ClusterError(f"The backend exited with {code}")
+
                 continue
 
             try:
@@ -681,7 +692,7 @@ async def _test_connection(self, timeout: int = 60) -> str:
                 asyncpg.CannotConnectNowError,
                 asyncpg.PostgresConnectionError,
             ):
-                time.sleep(sleep_time)
+                await asyncio.sleep(sleep_time)
                 continue
             except asyncpg.PostgresError:
                 # Any other error other than ServerNotReadyError or