newadmin: only allow bonsay hg mapping overrides when necessary

Summary:
This fixes a regression introduced with the port of the `derived-data` subcommand to `newadmin` (D49774292).

The old implementation that was deleted in D49779178 had the same behaviour as the code does after this change:
* Always override the lease for the derive subcommand
* Only override the bonsai hg mapping if `rederive` is passed

Reviewed By: YousefSalama

Differential Revision: D50735685

fbshipit-source-id: 4193c880bbd8d988e6292ca939cbdc6636041d68

eden/mononoke/tests/integration/test-newadmin-derive-regenerate.t

@@ -67,11 +67,16 @@
   $ mononoke_newadmin convert -R repo --from bonsai --to hg 1213979c6023f23e70dbe8845d773078ac1e0506bc2ab98382a329da0cb379a7 --derive
   52aee0f873361473bbb29cbce0c1ba5d0c1a2c5e
 
-# Now rederive HG_SET_COMMITTER_EXTRA=true. This changes hg hash, so let's run it with --rederive and make sure
+# Now rederive HG_SET_COMMITTER_EXTRA=true. This changes hg hash, so we need to run with --rederive and make sure
 # hg hash was overwritten.
   $ HG_SET_COMMITTER_EXTRA=true ENABLED_DERIVED_DATA='["git_trees", "filenodes", "hgchangesets"]' setup_common_config
-  $ mononoke_newadmin derived-data -R repo derive -T hgchangesets -i 1213979c6023f23e70dbe8845d773078ac1e0506bc2ab98382a329da0cb379a7 --rederive
 
-# Check hg hash after overwriting
+# If we call derive without the rederive flag, we have the same hg hash as before
+  $ mononoke_newadmin derived-data -R repo derive -T hgchangesets -i 1213979c6023f23e70dbe8845d773078ac1e0506bc2ab98382a329da0cb379a7
+  $ mononoke_newadmin convert -R repo --from bonsai --to hg 1213979c6023f23e70dbe8845d773078ac1e0506bc2ab98382a329da0cb379a7
+  52aee0f873361473bbb29cbce0c1ba5d0c1a2c5e
+
+# With rederive, we can see that the hash is now different as expected
+  $ mononoke_newadmin derived-data -R repo derive -T hgchangesets -i 1213979c6023f23e70dbe8845d773078ac1e0506bc2ab98382a329da0cb379a7 --rederive
   $ mononoke_newadmin convert -R repo --from bonsai --to hg 1213979c6023f23e70dbe8845d773078ac1e0506bc2ab98382a329da0cb379a7
   c4c28fe2943cad9b4fed5a6982d3ffc0a83b4e7e

eden/mononoke/tools/admin/src/commands/derived_data.rs

@@ -101,9 +101,7 @@ pub async fn run(app: MononokeApp, args: CommandArgs) -> Result<()> {
             .await
         } else {
             app.open_repo_with_factory_customization(&args.repo, |repo_factory| {
-                repo_factory
-                    .with_lease_override(|_| Arc::new(DummyLease {}))
-                    .with_bonsai_hg_mapping_override()
+                repo_factory.with_lease_override(|_| Arc::new(DummyLease {}))
             })
             .await
         }