fix: silence not found error when removing ephmeral (#4900)

We currently cannot drop tenant before removing it's directory, or use
Tenant::drop for this. This creates unnecessary or inactionable warnings
during detach at least. Silence the most typical, file not found. Log
remaining at `error!`.

Cc: #2442

pageserver/src/tenant/ephemeral_file.rs

@@ -266,11 +266,17 @@ impl Drop for EphemeralFile {
         // unlink the file
         let res = std::fs::remove_file(&self.file.path);
         if let Err(e) = res {
-            warn!(
-                "could not remove ephemeral file '{}': {}",
-                self.file.path.display(),
-                e
-            );
+            if e.kind() != std::io::ErrorKind::NotFound {
+                // just never log the not found errors, we cannot do anything for them; on detach
+                // the tenant directory is already gone.
+                //
+                // not found files might also be related to https://github.com/neondatabase/neon/issues/2442
+                error!(
+                    "could not remove ephemeral file '{}': {}",
+                    self.file.path.display(),
+                    e
+                );
+            }
         }
     }
 }

test_runner/fixtures/neon_fixtures.py

@@ -1504,9 +1504,6 @@ class NeonPageserver(PgProtocol):
             ".*Error processing HTTP request: Forbidden",
             # intentional failpoints
             ".*failpoint ",
-            # FIXME: there is a race condition between GC and detach, see
-            # https://github.com/neondatabase/neon/issues/2442
-            ".*could not remove ephemeral file.*No such file or directory.*",
             # FIXME: These need investigation
             ".*manual_gc.*is_shutdown_requested\\(\\) called in an unexpected task or thread.*",
             ".*tenant_list: timeline is not found in remote index while it is present in the tenants registry.*",