Unbreak delta reporting in benchmarks (#61236)

The logic here was apparently intended to omit literal zeros from deltas
to save a few bytes, but it instead drops all zeros from all columns.
Remove the condition that drops zeros in order to avoid confusing
the many scripts that consume this data.

Alternatives Considered

I'm probably going to entirely drop the delta form in an upcoming
PR, so I didn't think it was worthwhile to do something more complex,
such as:

* Fixing this logic to only omit zeros from actual delta columns

* Rewriting all the client scripts to treat any empty column as zero

benchmark/utils/DriverUtils.swift

@@ -665,8 +665,7 @@ final class TestRunner {
           (c.logMemory ? [r.meta?.maxRSS].compactMap { $0 } : []) +
           (c.logMeta ? r.meta.map {
             [$0.pages, $0.ics, $0.yields] } ?? [] : [])
-        return values.map {
-          (c.delta && $0 == 0) ? "" : String($0) } // drop 0s in deltas
+        return values.map { String($0) }
       }
       let benchmarkStats = (
         [index, t.name] + (results.map(values) ?? ["Unsupported"])