Configure ShipIt metadata for rebalancer getdeps build

Summary:
Add ShipIt configuration fields to the rebalancer fbcode_builder manifest so that `getdeps.py` can use the shipit pathmap and strip rules to create a local exported source tree for building.

- `shipit_project = rebalancer`: identifies the ShipIt project name
- `shipit_fbcode_builder = true`: enables fbcode_builder infrastructure for open-source builds
- `use_shipit = false`: disables automatic sync to GitHub while still allowing local getdeps builds

Reviewed By: sahilsd

Differential Revision: D93800832

fbshipit-source-id: 326316d6cea1ec2a2a99345deb173922b4f85e2b

Author: r-barnes

build/fbcode_builder/manifests/rebalancer

@@ -1,6 +1,9 @@
 [manifest]
 name = rebalancer
 fbsource_path = fbcode/algopt/rebalancer/
+shipit_project = rebalancer
+shipit_fbcode_builder = true
+use_shipit = false
 
 [git]
 # To git clone on devserver, setup fwdproxy: